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Part I. (First Fascicle) INTRODUCTION AND 
Prof. S. J. HICKSON, M.A., F.R.S. ; F. W. GAMBLE, 
D.Sc., F.R.S. ; A. WILLEY, M. A., D.Sc., T.R.S. ; J. J. 
LISTER, F.R.S. ; H. M. WOODCOCK, D.Sc. ; and the late 
Prof. WELDOK. 

Part I. (Second Fascicle) INTRODUCTION AND 
PROTOZOA. By J. B. FARMER, D.Sc., M.A., F.R.S. ; 
J. J. LISTER, F.R.S. ; E. A. MINCHIN, M.A. ; and S. Jv 



M.A., assisted by J. W. GREGORY, D.Sc., and E. S. 









K.C.B., M.A., LL.D., F.R.S. 












F. W. GAMBLE, D.Sc., F.R.S. 


A. WILLEY, M.A., D.Sc., F.R.S. 





















THE two fascicles of the first part of this treatise give a more 
complete account of the Protozoa than is to be found in any 
similar work hitherto published. Especial attention has been 
given to the treatment of those groups the Sporozoa r 
Flagellata, and Hsemoflagellata which have recently acquired 
so much importance in consequence of the discovery that some 
of their constituent members are the causes of important 
diseases in man and animals. 


December 1908. 






B. THE HELIOZOA . .... 14 

,, C. THE MYCETOZOA . . . . . 37 

D. THE LOBOSA ...... 68 




FORMS . . . . . . .193 



INDEX 287 

vii b ' 



THERE are certain matters which require brief treatment by way 
of introduction to the present treatise on Zoology. 

The first concerns the limitation of the subject-matter indicated 
by the term " Zoology," requiring a statement of what living things 
are here considered as animals and what are excluded from that 
title. The second concerns the grouping of animals in large series 
corresponding to the indications afforded by their structure as to 
their genetic affinities. The method adopted in the present work 
has been to take large divisions of the Animal series such as are 
often called " sub-kingdoms " or " phyla " (or in some instances less 
comprehensive divisions) one by one for systematic description and 
for more detailed enumeration and justification of the classes, orders, 
and families recognised than is usual in handbooks of Zoology. 
These large divisions have been assigned for treatment to separate 
authors, and in each case the author has given a description of the 
characters which justify the recognition of the group which he 
treats as an independent series ; to this he has added a more 
extended discussion of the range of variety in the structure of the 
forms held to be reasonably considered as members of the series. 

A special chapter written by me forms the introduction to 
volume ii. of this work. It may be regarded as a continuation of 
the present chapter, and treats of the division of the higher grade 
of animals, which is called the Metazoa (the lower being the 
Protozoa), into two branches, the " Parazoa " and the " Enterozoa." 
It is, however, chiefly occupied with a discussion of the division 
of the Enterozoa into two grades of higher and lower structural 
complexity, which are designated respectively the " Enterocoela " 
and " Coelomocoela." The chief phyla or large branches of the 
animal pedigree are there enumerated, whilst each is subsequently 
treated by independent authors. 

In the present introductory chapter I have therefore to consider, 
besides the question as to what distinctions separate animals from 

1 By Sir Ray Laukester, K.C.B. 



other living things, the facts which render it necessary to recognise 
two great primary grades of animals a lower called the Protozoa 
and a higher called the Metazoa. 


Living things Bionta are without difficulty, and by the 
general agreement of both skilled naturalists and the observant 
layman, divided into two greatly differing groups or series, the 
animals or Zoa and the plants or Phyta, and into those two great 
groups only. The study of the one series is called Zoology, and of 
the other Phytology, or more usually Botany. It is easy to lay 
down certain general propositions by which nearly all animals are 
distinguished from nearly all plants. The distinctions which can 
be thus indicated all arise from one great difference in the chemical 
activity of the living substance of an animal as compared with that 
of a plant. Although the living substance of both animals and 
plants, to which Hugo von Mohl gave the name Protoplasm, appears 
in both series in the form of nucleated corpuscles called cells, 
and although the formal appearances and the range of chemical 
activities exhibited both by the general protoplasm and by the 
nuclear structures of the cells of animals and plants are practically 
identical, yet there is a predominant difference in the habitual 
exhibition of their activities which separates animals from plants, 
and has determined the difference of form and activity characteristic 
of the living things assigned to either of the two groups. 

Living protoplasm, whether of animal or plant, undergoes 
(when the processes of life are not, as they may be for a short or 
for a very extended period, suspended) constant chemical change, 
requiring the access of free oxygen to the protoplasm and the 
consequent oxydation of some of its material which becomes 
" wasted " or lost and carried away by diffusion from the living 
protoplasm. This loss has to be replaced, and the process by which 
it is replaced is " nutrition " ; the material taken by a living thing 
for the purposes of nutrition is its "food." 

The result of nutrition is not limited to the repair of loss in 
the living thing, but is for a part or the whole of its existence 
in excess of the loss ; so that increase of the bulk of the living 
material or "growth" is a result. The elements carbon, hydrogen, 
oxygen, and nitrogen, combined to form molecules of the highest 
degree of complexity, are the essential constituents of living 
material. It is these that are oxydised and wasted and pass from 
the living thing during life : it is these which have to be replaced. 

Animals are unable to assimilate, that is, to utilise as food, the 
simpler chemical compounds of carbon or of nitrogen. They can 
only take their nitrogen from food which is in the elaborate form of 


combination which is called a proteid ; they can only take their carbon 
either from a proteid or from a carbohydrate or a hydrocarbon. 

These elaborate compounds only occur in the bodies of other 
animals or of plants. Hence animals absolutely depend for their 
food on other living things. Plants, on the contrary, are (with 
certain exceptions) able to take up as food the compounds of carbon 
and of nitrogen which may be called the stable or resting condition 
of those elements namely, the simple oxide of carbon carbonic 
acid gas and the simple compound of nitrogen with hydrogen which 
is called ammonia, or the oxide of nitrogen which forms nitrates. 
This " food " of plants is diffused throughout the earth's surface in 
air and water; hence they need to expose a large absorbing surface 
to those media ; hence their branches and leaves spread in tree- 
like form to the air or to the water, whilst their roots are spread to 
the water contained in the soil. Their food is ever moving and 
flowing around them : they have neither to move in search of it 
nor to seize it. Hence the majority of plants are fixed and find 
safety and protection in stability. Animals, on the other hand, have 
to obtain their food from the scattered, solid, separate bodies of 
plants or of other animals. They have to move in search of it, they 
have to seize it when found, and they have to act chemically on 
the solid or viscous body or fragment of their prey so as to dis- 
solve it and to enable the dissolved material containing the precious 
carbon and nitrogen in a high state of chemical combination to 
diffuse into their living substance and there be further assimilated 
and built up into the material of protoplasm. For these purposes 
animals possess structures enabling them to move more or less 
rapidly, and others enabling them to seize or grasp. Further, and 
of even more fundamental a character as determining their whole 
shape and organisation, they possess (with rare and intelligible 
exceptions) an aperture, the month, leading into a relatively extensive 
cavity, the gut, into which the solid or viscous mass of food is intro- 
duced, and when there is chemically dissolved or " digested." 

The obvious and predominant difference in the make and habit 
of plants as compared with animals is thus connected with the very 
great and definite difference in the nature of the food of the two 

These statements are true in a general way, but require 
qualification. In the first place, we find it necessary to regard as 
genetically part of the great Plant series many organisms which are 
not able to procure their carbon from carbonic acid nor their nitro- 
gen from ammonia. Only the green plants are able to perform this 
constructive feat. The protoplasm of the more superficial cells of 
green plants contains corpuscles impregnated with a transparent 
green matter known as chlorophyll. In the presence of and in 
virtue of the physical action of sunlight screened by their chloro- 


phyll, the protoplasm of these cells has the property of decompos- 
ing carbonic acid, liberating free oxygen, and combining the carbon 
with hydrogen and oxygen to form starch. This is the critical step 
in the interaction of chemical elements on the earth's surface, by 
which life is at present determined. Were there no assimilation of 
carbon from carbonic acid to form starch by the green plants 
the whole fabric of the living world would tumble to the ground in 
truth, become mineralised. All living matter breaks down, within a 
short space of hours or days, to the resting or mineral condition of 
carbonic acid and ammonia (or nitrates). Were the building-up 
process, the raising to higher potentiality, not incessantly performed 
by green plants a power which chlorophyll and chlorophyll alone 
confers on them all carbon must pass from the reach of the organic 
world and living matter come to an abrupt end. 

And this is equally true of nitrogen. The nitrogen present in 
living protoplasm tends inevitably to the stable inert condition as 
a nitrate, as ammonia, or as the pure dissociated atmospheric gas. 
It is only by a subtle chemical process which occurs in the green 
plant as a result of and in connection with the fixation of carbon 
as starch that nitrogen taken up in water by the roots of the plant 
as nitrate and as ammonia is brought into combination as part of an 
" organic " compound or molecule. Thus in the ultimate history of 
the chemistry of living things the animal depends for its necessary 
food proteids, carbohydrates, and hydrocarbons on chlorophyll, 
the " leaf-green " of green plants. Vegetarian animals swallow 
and digest these substances built up by plants ; carnivorous animals 
swallow and digest animals which have already profited by the 
work of the green plant. No animal can take up even a fraction 
of a grain of carbon or nitrogen from a stomachful of carbonates, 
nitrates, and ammonia. 

There are, however, as exceptions plants which are devoid of 
chlorophyll and depend upon the results of the constructive activity 
of other plants and of animals, just as per contra there are ex- 
ceptional parasitic animals which have no mouths or gut and live 
in the diffusible nutritive juices elaborated by other animals, which 
they absorb by the surface of their bodies. The chemical life of 
those plants which are devoid of chlorophyll the fungi, the 
bacteria, and a few others may be considered as corresponding in 
character to that of those tissues or cell-groups of green plants 
which lie within the green plant and are devoid themselves of 
chlorophyll. Both these tissues and the autonomous fungi and the 
saprophytes depend for their food on the products supplied to 
them by the chlorophyll-holding cells of green plants. There are 
minute filamentous and rod-like plants devoid of chlorophyll 
(Bacteria and others) which can take their carbon as tartaric acid 
and their nitrogen as ammonia. It is probable that all such non- 


chlorophylligerous plants must be regarded as derived from chloro- 
phyll-bearing ancestors by adaptation to a food already somewhat 
raised by other organisms above the lowest stage of carbon- 

Again, there are amongst the most highly developed flowering 
plants examples here and there of the exceptional and special 
development of stomach-like organs with mouth-like openings into 
which insects are attracted, and when once entrapped are held 
either by the actual movement of a grasping organ or by other 
mechanical apparatus, and are digested by chemical secretions 
identical in character with those of the animal stomach, the digested 
product being absorbed and serving to nourish the plant. Such 
cases, whilst they demonstrate in a most striking way the essential 
identity of the faculties of the living protoplasm of plant and 
animal, do not invalidate the fundamental proposition, that plants 
are a series of organisms which have developed their distinctive 
form and structure as feeders on the diffused carbonic acid, ammonia, 
and nitrates of the circumambient medium ; whilst animals are a 
series which have developed their distinctive form and structure 
as feeders on scattered often elusive live or dead bodies or solid 
particles of other animals or of plants, that form being essentially a 
locomotive sac with a mouth. Amongst the larger animals, those 
visible to the naked eye, there are few exceptions to this rule. 
Such exceptions are found in the obviously exceptional and therefore 
aberrant internal parasites which require no mouth nor digestive sac. 

But there are a few, very rare cases of small aquatic animals 
which are provided with chlorophyll-corpuscles and obtain a part 
(in one case, the worm Convoluta, the whole) of their nutriment 
in the same Avay as does the green plant, namely, in virtue of the 
assimilation of carbon from carbonic acid in the chlorophyll- 
bearing tissue when under the influence of sunlight. The 
chlorophyll-bearing cells of the worm Convoluta and of many 
Anthozoa have been shown to be unicellular parasites which have 
established the closest relationship to their hosts. But it is by no 
means demonstrated that the chlorophyll-corpuscles of Spongilla and 
of Hydra are parasitic in origin. 1 The fact that they are not 
chlorophyll-bearing cells, but simple non-nucleated corpuscles with 
a cortex impregnated with chlorophyll precisely comparable to the 
chlorophyll corpuscles of green plants, does not permit us to 
consider them as parasites which have effected a lodgment and 
association with Spongilla and Hydra with any more reason than 
we can adduce for so regarding the similar corpuscles in green 
plants. The view has been seriously advanced that the latter are, 

1 See on this subject my memoir on "The Chlorophyll-corpuscles and Amyloid 
Deposits of Spongilla and Hydra" in vol. xxii. (1882) of the Quart. Journal of 
Microsc. Science. 


in fact, also parasites. This may prove eventually to be susceptible 
of something like demonstration, but in the meantime we must 
ask where the limit to this assumption that chlorophyll is of 
parasitic origin is to be placed. 

It cannot be that all chlorophyll even that observed in all uni- 
cellular plants and animals is to be regarded as " parasitic." And 
if we are once able to distinguish certain independent unicellular 
organisms which actually manufacture chlorophyll Avithin them- 
selves by the activity of their own protoplasm, we shall be able to 
study the steps of that process and to judge as to whether the 
protoplasm of the green cells of green plants and of the freshwater 
sponge and of the green Hydra do or do not form chlorophyll 
plastids in the same way and in virtue of the same protoplasmic 
capacity as do minute unicellular algae. 

There is no reason, a priori, for refusing to ascribe to a tissue- 
cell of a Sponge or a Hydra the same capacity to form a chemical 
deposit of any kind which a free unicellular organism possesses. 
Unfortunately this is not a case in which the simple test of observa- 
tion can be applied, so that the question as to whether the tissue- 
cell does construct a chlorophyll -corpuscle or does not can be settled 
by inspection. The intricacies of structure and growth are in this 
matter such as to render direct observation difficult and illusive. 

Whilst there are, then, exceptional cases in both plants and 
animals as to the great nutritional distinction between the two 
series, it is comparatively easy in all excepting the very lowest 
forms to satisfy ourselves that the departures from the rule are 
specialised derivatives from the main series. The colourless or 
greenless plants are descended from green chlorophylligerous 
ancestors ; mouthless, gutless animals are descended from mouth- 
bearing, gut-hollow animals. 

When, however, we come to the very lowest unicellular micro- 
scopic forms of life, there is greater difficulty in assigning some of 
the minuter organisms to one side or the other, and to some extent 
our decision in the matter must depend on the theory we may 
provisionally adopt as to the nature of the earliest living material, 
which was the common ancestral matrix from which both the 
Plant series and the Animal series have developed. The real 
question in regard to such a theory is as to whether we find 
reason to suppose that the combination of carbon and nitrogen to 
build up proteid, and so protoplasm, required, in the earliest state 
of the earth's surface, the action of sunlight and the chlorophyll 
screen. We must remember that, though these are now necessary 
for the purpose of raising carbon, and indirectly nitrogen, from the 
mineral resting state to the high elaboration of the organic mole- 
cule, yet it is, after all, living protoplasm which effects this marvel 
with their assistance ; and it seems (though possibly there are some 


who would deny this) that it is protoplasm which has, so to speak, 
invented or produced chlorophyll. Accordingly, I incline to the 
view that chlorophyll as we now know it is a definitely later evolu- 
tion an apparatus to which protoplasm attained, and as a conse- 
quence of that attainment we have the arborescent, filamentous, 
foliaceous, fixed series of living things called plants. But before 
protoplasm possessed chlorophyll it had a history. It had in the 
course of that history to develop the nucleus with its complex 
mechanism of chromosomes, and it had during that period to 

The suggestion has been made long ago (see article " Protozoa," 
Ency. Brit, 6th edition), and appears to me not improbable, 
that by whatever steps of change that high complex of organic 
molecules which we call protoplasm the physical basis of life came 
into existence, it very probably fed in the first few aeons of its 
existence on the masses of proteid-like material which, it may be 
supposed, were formed in no small quantity as antecedents to the 
final evolution of living matter. If this were the case, the mode of 
nutrition of the first living things must have been similar to that 
of animals and unlike that of plants. At a later stage chlorophyll 
was evolved, the decomposition of carbonic acid became possible, 
and the Plant series was started. 

In accordance with this conception, we must look for the 
representatives of the most primitive forms of life amongst the 
minute Protozoa, possessing the simplest methods of nourishing 
themselves by the digestion of already elaborated proteid. Such 
are the Mycetozoa, which digest dead organic material by contact, 
creeping in the form of naked plasmodia of many inches in area 
over organic debris ; such, too, are the minute single cells of naked 
protoplasm taking in particles of proteid food by extemporised 
mouths and digesting them in the cell-body, whilst prehensile and 
motor organs are furnished by the extension of the cell-protoplasm 
in the form of lobose processes, radiating filaments, or single or 
double vibratile flagella. The earliest plants, the Protophyta, 
were, it seems most probable, derived from flagellate colony- 
building Protozoa (similar to the Volvocinese), which had, at first 
without discarding their animal-mode of nutrition (Zootrophic), 
acquired the faculty of manufacturing chlorophyll and supplementing 
their ingested nutriment by the decomposition of carbonic acid and 
the fixation of nitrogen (Mixotrophic). The step from this to a 
purely chlorophyll-given nutrition (Phytotrophic) was not a long 
one, and indeed occurs in the life-history of some of the Flagellata 
at the present day. With the establishment of pure Phytotrophic 
nutrition ensued the formation by simple cell-division and element- 
ary variation of cell-aggregation of filamentous green plants consist- 
ing of chains of cells in single series ; to these followed networks of 


such chains, then growth and division of the still-connected cells 
in two and finally in three dimensions, producing first sheet-like 
and finally more solid structures, the constituent cells of which 
became variously differentiated and specialised. 

Those extremely minute, thread-like (Leptothrix, Spirillum), or 
rod-like (Bacillus) plants devoid of chlorophyll, which often break 
up without losing vitality into spherules or into granules of 
even ultramicroscopic tenuity, known as the Schizomycetes (or 
colloquially Bacteria), cannot be considered as primitive. Like the 
Fungi and many of the most highly organised plants, they have 
descended from chlorophyll-bearing forms, and have become adapted 
to a parasitic or saprophytic mode of nutrition whilst retaining 
the general characteristics of growth and form of their ancestors. 
The intimate connection of the Schizomycetes with the Oscillatoriae 
does not seem to admit of any doubt, and forms closely allied to them 
develop chlorophyll as well as peculiar blue and red pigmentary 
substances, the function of which is obscure but may be related 
to their modified nutritional processes. We are thus led to regard 
all the non-filamentous, non-chlorophylligerous microscopic forms 
which are not referable to the Schizomycetes or to the simpler 
Fungi as "Protozoa." The debatable ground is limited to the 
chlorophyll-forming Flagellata, amongst which are some which, 
being devoid of mouth and at all periods of their growth incapable 
of zootrophic activity, are yet so closely allied in life-history and 
structure with truly zootrophic species that it is not possible to 
draw a sharp line and assign them definitely either to the Animal 
or to the Plant series. Such are the Volvocineans, which zoologists 
will probably for some time to come consider it desirable (as we do 
in the present treatise) to treat of in the description of the Animal 
series, whilst botanists will find it equally desirable to discuss 
them in connection with closely allied minute Plants. 

In view of these considerations, we consider the following 
groups of the simplest organisms as belonging to the Animal 
series, and as constituting a lowest " grade " of animal organisa- 
tion, to which the term Protozoa is applicable. The groups in 
question are given the title of "classes," but it will readily be 
understood that it is not intended to imply by that term that 
they have any exact equivalence in the amount of divergence 
from one another to that which is presented by the " classes " of 
any one of the phyla of the Metazoa. 

PROTOZOA. Class 1, Proteomyxa; Class 2, Heliozoa; Class 3, 

Mycetozoa ; Class 4, Lobosa ; Class 5, Radiolaria ; Class 6, 

Mastigophora ; Class 7, Sporozoa; Class 8, Ciliata; Class 9, 



Formerly the name Protozoa was used for a sub-kingdom of the 
Animal Kingdom equivalent in value to other sub-kingdoms which 
were enumerated as the Coelentera, the Vermes, the Arthropoda, the 
Echinoderma, the Mollusca, and the Vertebrata. In its earlier use 
the great division " Protozoa " was made to include the Sponges, 
which we now assign to a divergent line of descent, the Parazoa, 
opposed to the main line, the Enterozoa, in the higher grade of 
animals called the Metazoa. The removal of the Sponges from 
association with the Protozoa is chiefly due to the initiative of 
Ernst Haeckel. By this step it became possible to give something 
like a definite characterisation of the Protozoa and to mark them 
off from all the higher animals. They are definitely characterised 
by the fact expressed in the English name Cell-animals (Plasti- 
dozoa), or less correctly unicellular animals, whilst all the higher 
animals or Metazoa (inclusive of the Sponges) are Tissue-animals 
(Histozoa). The fact indicated in these terms is that in 
Protozoa a single cell or a colony of equi-pollent cells is the 
organic "individual," whilst in the Metazoa the "individual" 
is built up by cells which are differentiated into at least two 
layers or tissues, the cells of each tissue being of like value 
and origin with its fellow -cells of that tissue, but differing 
essentially in structure, function, and origin from the cells of the 
other tissue or tissues. These statements will be found on critical 
examination to hold good in view of our present knowledge of both 
Protozoa and Metazoa. Most of the Protozoa are unicellular, and 
in those which form many-celled colonies, such as the Mycetozoa, 
some of the Iladiolaria, Mastigophora, Ciliata, and Acinetaria, there 
is no tendency for those cells to differentiate into groups of cells of 
like structure and function to one another, but differing in structure 
and function from another group or groups present in the same 
colony. The only approach to an exception to this generalisation 
is found in the specialisation of a cell here and there in the colony 
as a reproductive cell; but, on the other hand, it is to be noted that any 
cell in the colony is potentially a reproductive cell, and there is no 
differentiation of a congeries or tissue of cells for reproductive pur- 
poses in the general plan of the colonial structure. 1 It appears to 
be the fact that we do not know of any forms at present existing 
which furnish a transition from Protozoa to the Metazoa. There 

1 Though the existence of at least two "tissues" in the Metazoa suffices to dis- 
tinguish them from all Protozoa, it may legitimately be contended that the congeries 
of cells forming the colony of certain Protozoa (e.g. Volvox) is rather of the nature of 
a "tissue" than of a merely loosely adherent association of cells which, as we see 
in many Protozoan colonies, can and do separate freely and irregularly from such 


have been descriptions of supposed independent organisms sug- 
gesting such intermediate character (Trichoplax and others), but 
the true nature and history of these structures have not been placed 
on a definite basis, and do not really admit of discussion. The 
nearest case of a transitional form appears to be the Choano- 
flagellate " Proterospongia " of Savile Kent, which has been 
observed on several different occasions from different localities. 
It combines in one colony " amoebocytes " and " choanocytes," but 
it appears that the one form of cell develops into the other. It is 
certainly not unreasonable to regard Proterospongia as a step 
forward from the Choanoflagellata in the direction of the Parazoa. 
There is no instance of equally definite character tending to 
connect Protozoa of any class with the Enterozoa. 

Until recently it was possible to add to this distinction between 
Protozoa and Metazoa the very striking one that all Metazoa 
reproduce by means of fertilised egg-cells (as well as by other 
processes), such fertilised cells being the result of the union of 
specially developed egg-cells and sperm-cells. Conjugation of two 
cells similar to one another as a preparation to multiplication by 
fission was known and described in several Protozoa, but the special 
units, the static female egg-cell and the motile male " spermatozoid," 
were unknown in Protozoa. The apparent exception to this pre- 
sented by some of the Volvocinean Flagellata was regarded as a 
reason for assigning these organisms to the pedigree or great series 
of Plants, thus removing them from association with the other 
Flagellata. In the Plant series, though many groups both among 
the highest and lowest do not present sexual reproductive elements 
under the typical forms of egg-cell and spermatozoid (antherozoid), 
yet some of the lowest and simplest, as well as some of the higher, 
plants do develop motile conjugating " male " cells, which seem to 
render the relegation of Volwx to the vegetable series a reasonable 
proceeding. Within the last decade, however, we have not only 
become acquainted among undoubted Protozoa with instances 
of the development of " microgametes " or small conjugating cells, 
Avhich are distinguished by their size from the larger egg-cells 
or " macrogametes " with Avhich they fuse in order to form a 
fertilised "germ," but we now know undoubted Protozoa which 
exhibit the breaking up of a parent male unicellular individual into 
a number of motile microgametes. These have the appearance and 
characteristics of the spermatozoa of higher animals, are developed 
from the parent male cell by the same steps as are spermatozoa 
from sperm-mother-cells, and proceed to fertilise the female macro- 
gametes in the same manner as occurs in the fertilisation of the 
egg-cell in Metazoa. 

The Coccidiidae among the Sporozoa and certain of the Haemo- 
flagellata are the Protozoa in which this phenomenon has been 


carefully observed. It is identical in its essential features with the 
sexual reproductive phenomena of the colonial Flagellate, Volvox 
fjlobator. Not only so, but the egg -cells and spermatozoa thus 
developed and uniting are identical in character with the egg-cells 
and antherozoids of a vast series of lower and higher plants, and 
with those of the whole series of Metazoa. A very important link 
in the genetic relationships of Plants and Animals is thus established. 
There is no occasion to suppose that they have independently 
developed the typical form of the male and the female reproductive 
particles. The plants have inherited this from the Protozoa which 
gave rise to the earliest chlorophylligerous, phytotrophic organisms. 
It is perhaps necessary to remark that further observation is 
necessary in these lowest forms as to the precise steps in the 
preparation of the nucleus and its chromatin in each of the 
conjugating gametes for the definite union of fertilisation. There 
is abundant evidence that it is of the same nature as that which 
occurs in the sexual cells of higher organisms, but in special details 
we may have to recognise some differences. 


The question as to whether the various classes of Protozoa are 
to be regarded as nine separately divergent lines of descent, starting 
from a common primitive ancestry not represented at the present 
time by any one of them, or whether some of them possess closer 
genetic relationship inter se than do others, is a very difficult one. 
It has been proposed at various times to seek for evidence of such 
closer affinity in the development of a cortical firmer layer of the 
cell-protoplasm (as in most Sporozoa and in the Ciliata), as opposed 
to the retention of the uniform viscid character of the protoplasm 
(Lankester, Ency. Brit., article "Protozoa"), and again it has been 
considered probable that all those forms which produce temporary 
lobose or filnmentar extensions of the protoplasm, as locomotor or 
grasping organs, may have a genetic community of origin which 
separates them from those provided with either isolated flagella or 
with " cilia " of vibratile protoplasm. Some or other, however, of 
the forms which it is found necessary, on account of the affinities 
indicated by their life-histories and other details of structure, to 
class as Flagellata (Mastigophora) exhibit combinations of characters 
which render both these attempts at grouping unsatisfactory. 

We find Flagellata (see the section on this group) which produce 
extensive amoeboid processes, and yet possess a flagellum, whilst 
the majority have a distinctly corticate protoplasm. Among the 
Sporozoa (for which refer to the section on that group in the second 
fascicle of Part I. of this treatise), which are with these rare excep- 
tions strongly corticate, we find genera which produce lobe-like and 


pointed "pseudopodia" from their superficial protoplasm (Zygoco- 
metes and others). It seems that in any attempt at a phylogeny of 
the Protozoa we should have to treat the assemblage of forms now 
classed as Mastigophora (Flagellata) as a central group from which 
the other eight classes have been derived, whilst embracing in 
itself several specialised lines of descent, including that which has 
given rise to the primitive green plants. 

The indication of a higher and later elaboration of structure, 
as distinct from a lower and more primitive, by means of the 
classifieatory artifice of " grades," has, however, been introduced in 
the present work by Professor Hickson in regard to the classes of 
Protozoa by a consideration of the cell -nucleus. The condition 
of this important structure justifies, he considers, the separation of 
the classes of Protozoa into a lower and a higher grade the 
Homokaryota and the Heterokaryota and it is not improbable 
that further study of the lower grade will lead to the subdivision 
of that assemblage into sub-grades. 

The history of the nucleus of the corpuscle of protoplasm, that 
corpuscle which it is customary to regard under the name of " the 
cell " as the unit of living structure, is at present absolutely un- 
known and altogether a matter of conjecture. It may perhaps be 
conceded as highly probable that the earliest protoplasm was with- 
out nucleus or differentiated nuclear material. It is a legitimate 
contention that such a substance should not be called " protoplasm " 
at all, since Hugo von Mohl- invented this term to describe the 
viscid contents of a vegetable cell expressly including the nucleus 
a? part of it. It was proposed some twenty-five years ago by 
Ed. van Beneden to call the earlier non-nucleated stage of living 
matter "plasson," and it seems to me by adopting this term we 
can preserve the word " protoplasm " for its original use. At the 
same time it is important to avoid using the word " protoplasm," as 
is not unfrequently done, to signify the critical chemical body which 
undoubtedly is present in living protoplasm and is the apex of the 
pyramid or the top of the fountain, to which a variety of chemical 
bodies are leading and from which another series of chemical bodies 
are receding at every moment of the chemical activity of living 
protoplasm. Protoplasm is not a chemical body but a structure, 
and its nuclear particles, as well as its definitely formed nucleus 
consisting of chromatin and other constituents, are parts of it. It 
seems necessary to have a word by which to refer to the highest 
group of chemical molecules to which one set of chemical processes 
in the cell are always leading and from which another series are reced- 
ing. I proposed some years ago (Ency. Brit., article "Zoology") 
to speak of this hypothetical body as " plasmogen." In the same 
way it is necessary to avoid the tendency which exists to employ 
the word " protoplasm " to describe cell-substance both when con- 


sidered as apart from the nucleus and when actually existing in an 
unmanipulated simplest living thing without any nucleus or nuclear 
matter. We have seen that " plasson " is the name which has been 
proposed for the latter ; for the former the word " cytoplasm " is 
frequently used, whilst " nucleoplasm " is applied to that part of the 
cell-protoplasm which is the nucleus. The use of the word " cyto- 
plasm " in this sense is certainly objectionable, as it signifies " the 
cell-plasm " and is merely a synonym of " protoplasm." It would 
be better to term the extra-nuclear substance of the protoplasmic 
corpuscle " periplasm." 

As a hypothesis we may assume that living matter was at one 
time in the condition of " plasson," though it has yet to be shown 
that " plasson " is in existence at all at the present day. The 
next hypothetical stage is the development in distinct granular 
form of the material which later became aggregated as a nucleus. 
We may apply the word "protoplasm" to this stage, with a 
qualifying adjective, " konio-karyote " (powder-nucleated). This 
condition is known as actually existing in certain phases of the 
ciliate Protozoa (Trachelocerca), and possibly is to be recognised 
in some degenerate Protophyta and in some of the Proteomyxa 
(whether degenerate or archaic) amongst Protozoa. The third stage 
in the hypothetical development of protoplasm consists in the 
aggregation of the scattered nuclear granules to form one or more 
nuclei of definite structure and properties. Usually but one such 
nucleus is formed, but to cover the case of the existence of two or 
more similarly organised nuclei the term Homokaryote (proposed 
by Professor Hickson) may be used for this condition. The nucleus 
of the Homokaryote cell is in leading features of its structure 
identical with that of the tissue-cells of higher organisms. It 
consists of nuclear capsule, nuclear hyaloplasm, and of chromatin 
elements. The optical, chemical, and physiological analysis of the 
nuclei of Protozoa and Protophyta has not been extended to a 
sufficient number of instances, at present, to render it possible to 
trace the steps (if they are still traceable) by which the complete 
structure of the nucleus and its activity in cell-division were evolved. 
It is not yet clear whether there are among Protozoa and Proto- 
phyta any surviving simpler phases of the nucleus, or whether 
apparently primitive phases which are described are so interpreted 
owing to incomplete observation or, on the other hand, owe their 
simplicity to a degeneration from a more highly developed condition 
of the nucleus. It is, however, certain that there are cases amongst 
the Protozoa in which the structure and activity of the nucleus in 
cell-division conforms very closely to those of the tissue-cells of 
higher animals and plants, if not absolutely identical with them. 

There are, however, in certain Protozoa special modifications of 
the nuclear structure which have not yet been shown to occur in 


Metazoa, nor in plants. The most striking of these is the division 
of the nucleus in Ciliata and Acinetaria into two unequal and 
dissimilar portions, the mega-nucleus and the micro-nucleus, which 
appear to be the portions of the primary nucleus which preside 
over the somatic (the larger) and reproductive activities (the 
smaller) respectively. Professor Hickson has made use of this 
differentiation of the nucleus into two parts in order to establish 
a higher grade of the Protozoa the Heterokaryota as distinguished 
from the Homokaryota. 

Amongst those forms, however, which are classed by him as 
Homokaryota, there are (as he recognises) certain forms amongst 
the Flagellata which also exhibit a differentiation and segregation 
of the nucleus, but with functions for the separated elements 
different from that shown in the Ciliata. This case is that of the 
formation of a separate nuclear body, the kineto-nucleus, in con- 
nection with, and apparently controlling the activities of, the large 
and powerful flagellum of certain flagellate forms (Trypanosoma, 
Noctiluca). It seems that the word Heterokaryote would strictly 
apply to these forms also, although the "heterosis" is not the 
same as that seen in Ciliata. It would be premature to attempt to 
introduce a terminology indicating these different specialisations of 
nuclear structure in the Protozoa until much further study has 
been given to the subject. It is not at all improbable that researches 
which are now in progress will in the course of a few years giA^e 
us, first of all, a better understanding of the chemical nature and 
activities of the substances which are merely brought into view 
by colour-staining as form-elements in the nucleus, 1 and secondly, 
a far more critical knowledge than we at present possess of the 
rudimentarily aggregated and diffuse stainable matter which is 
interpreted as " nucleus " in some of the Protozoa, in some of the 
Cyanophyceae, in Schizomycetes, and in the yeasts and hyphae 
of lower fungi. 

Whilst therefore recognising the important separation of the 
Ciliata and Acinetaria effected by having regard to the nuclear 
structure of those groups and that of the other classes of Protozoa, 
so far as we at present know them, I am unwilling to emphasise the 
arrangement of the Protozoa into grades according to their nuclear 
structure in the present state of knowledge. I should not wish to 
go farther at present in grouping the classes of Protozoa than to 
suggest that they should be considered as diverging lines of descent 
radiating from a central group which possessed the combination of 
characters presented at the present day by the simpler Flagellata. 

1 The researches of Professor Macallum of Montreal iii this direction will, it 
may be hoped, be continued and developed. 



IN the study of the Protozoa a number of forms are found 
which are difficult to place in any of the larger orders or families. 
The difficulty arises in many cases from what is called their 
simplicity of structure, and partly from our ignorance of their entire 
life-history. The more we learn of the structure of the Protozoa, 
the more hazardous does it become to apply the expression " simple " 
to any living organism, but what is really meant by the term 
" simple " as applied to these organisms is that they exhibit no 
definite structure or structures such as skeleton, flagella, or nuclei 
that are so constant in their form and character that they can be 
seized upon by the systematist and used for purposes of classifica- 
tion. When characters of this description appear during one phase 
only of the life-history of an organism they may indicate its 
affinities if not its true systematic position, but when the life-history 
is not completely known there may be no characters which can 
possibly serve for placing the organism with others in any 
system of classification. In the early history of Protozoology there 
was a time when it was considered that some of the very small 
and obscure organisms consisted of a cytode of protoplasm in 
which there was no structure corresponding with the nucleus of the 
higher organisms and cells. Such organisms were placed in a class 
Monera by Haeckel in 1868. Subsequent researches proved that 
in many of these organisms one or many minute structures occur 
which give the same reactions as the chromatin of the nucleus, 
and the conclusion was, in some cases too hastily, drawn that all 
of them would in time be shown to be nucleated. Modern 
researches on the nuclear structures of Protozoa have thrown 
much light on this vexed question. They have shown that the 
nucleus may discharge into the cytoplasm, or give rise by total 
fragmentation to, a number of minute granules of chromatin the 
chromidia and that these granules do not degenerate, but retaining 
their vitality may again aggregate together in the formation of new 
nuclei. There may thus occur in the life-history of the higher 
Protozoa a stage which is strictly speaking non-nucleate (akaryote). 

1 By Prof. S. J. Hickson, F.R.S. 

1 i 


This does not imply, however, that the organism is at this stage 
devoid of nucleoplasm, but that the nucleoplasm is not concentrated 
in the form of a definite nucleus or kernel but is scattered or 
diffused. This conception may be expressed by saying that the 
stage is akaryote but is not moneran. There is no nucleus but 
there is nucleoplasm. In Amoeba, Pelomyxa, and others in which 
such a stage occurs the nucleus is present during the greater 
part of the life-cycle, the akaryote stage being antecedent only to 
nuclear multiplication or gametogenesis. 

In the Proteomyxa, on the other hand, the akaryote condition is, 
as a rule, of much longer duration, and it is possible that in some 
cases the diffused nucleoplasm or scattered chromidia do not collect 
together in any stage to form a defined nucleus. 

It seems probable, then, that the protoplasm of the Proteomyxa 
really represents the protoplasm of the higher Protozoa and 
Metazoa plus the substance of the nuclei. It is a substance which 
van Beneden (9) in 1871 proposed to call "the plasson," that is, 
the formative substance "which is capable of becoming, either in 
ontogenetic course or in phylogenetic course, monocellular elements 
after that the chemical elements of the plasson have been separated 
to constitute a nucleus and a protoplasmic body." 

Our knowledge of the nucleus or chromidia of the genera that 
are here grouped together in the class Proteomyxa is at present 
very scanty. Vampyrellidium is said to have a nucleus m all stages 
of its life- history. Zopf states that a definite clear nucleus is 
present in all species of Fampyrella, but it is often obscured by 
chlorophyll and other bodies in the cytoplasm. There seems to be 
little doubt, however, that the nucleus is not present in all stages 
of the vegetative life of F'ampyrella, as several observers Avho 
have carefully re-examined its structure have failed to find any 
definite nucleus. Recently, however, Dangeard (13) has shown 
that nuclei are present in the cysts, and that they divide by karyo- 
kinesis. In Tetramyxa there are said to be minute nuclei, but these 
are probably chromidia. In Plasmodiophora true nuclei are un- 
doubtedly present at the time of spore-formation, as they have been 
observed to divide by karyokinesis. It is probable also that a 
defined nucleus is present during the flagellate and amoebula phases 
of most of the Proteomyxa (Fig. 8, B, H), but it is clear that for 
a time during the plasmodium stage the nuclei are disintegrated. 
In Endyonema nuclei appear to be wanting during the active vege- 
tative phase in the filaments of its host -plant (Lingbya), but 
definite nuclei are constituted when the body contracts in the 
formation of the zoocyst. 

Many of the genera included in the group have been seen only 
once, and we are still in ignorance of their nuclear condition, but 
in Gymnophrys, Biomyxa, Gloidium, Leptophrys, and Protamoeba, 


which have been studied by other observers than their original 
discoverers, no defined nuclei have been found. 

A considerable number of genera are parasitic upon freshwater 
algae during at least one stage of their life-history, such as Vam- 
pyrellidium, F'ampyrella, Leptophrys, Endyonema, Enteromyxa, Col- 
podella, Pseudospora, Gymnococcus, Aphelidium, Tetramyxa, and 
Ectobiella. Tetramyxa causes the formation of gall-like growths 
on Ruppict and other freshwater 
plants. Bursulla occurs in horse- 
dung. Haplococcus occurs in the 
muscles of the pig, but is appar- 
ently harmless. The only species 
that is of any economical import- 
ance is Plasmodiophora brassicae, 
Woronin, which attacks turnips FIO. i. 

and Causes the disease known as Ectotnella plaUaui. A, a specimen attack- 

,/T-T j rr\ JTT i >; ing Licmophora ; ps, the pseudopodium that 

" ingersand IOCS, Or "Hanbunes. is pushed into the substance of the host; v, 

A rrmsirW-iblp nnmbpr nf 0-pnpra the vacuole formed by the host containing 

A C OI genera granules pro duced by the digestive action 

are not parasitic and feed upon of the pseudopodium. B, tiie biflagiiate 

, , . zoospore of Ectobiella. (Alter de Bruyne.) 

minute animal and vegetable 

organisms. Such genera are Gymnophrys, Biomyxa, Protomyxa, 

Gloidium, and others. 

In the vegetative condition the body emits pseudopodia. These 
pseudopodia may be roughly arranged in three categories. 

In Protamoeba, Gloidium, Enteromyxa, etc., the pseudopodia are 
usually lobate like those characteristic of the genus Amoeba. 

In F'ampyrella, Colpodella, Monobia, Myxastrum the pseudopodia 
are radiate in position, very delicate and rarely anastomosing, like 
those of an Actinophrys. 

In Biomyxa, Gymnophrys, Penardia they are delicate and anasto- 
mosing, like the pseudopodia of the Foraminifera. 

In Endyonema, Haplococcus, Aphelidium,, and other endoparasites 
the form of the body is adapted to the spaces of the host and true 
pseudopodia are not formed. 

In Protomyxa, Myxastrum, Protomonas, Bursulla, Plasmodiophora, 
a. number of amoebulae unite to form a plasmodium, and it is 
possible that plastogamy also occurs in F'ampyrella, Leptophrys, and 
some others. In Monobia a number of stellate individuals unite to 
form an open network (Fig. 4). 

A contractile vacuole does not usually occur in Proteomyxa, 
but it appears to be a constant feature in Gloidium and Ciliophrys. 
Non-contractile vacuoles occur in many of the genera. 

Although very little is known about the life -history of the 
Proteomyxa, it seems probable that they all, at some time, form 
.cysts or spores. In Plasmodiophora the protoplasm of the plasmodium 
breaks up into a large number of simple spores, which are able to 


resist desiccation, and are probably simple hypnocysts. 1 In other 
cases the cysts are larger, and the contents give rise to three or 
four (Vampyrella lateritia, Fig. 2) or a large number (Protomyxa, 
x, Fig. 6, and Diplophysalis) of spores, which may be 
either naked or protected by a membrane. These 
cysts are protected by one or more cyst-membranes, 
and the outer of these may be irregular or spiny or 
gelatinous in texture. Occasionally three or four 
small areas on the cyst-wall are provided with a 
thinner membranous coat, and the spores escape by 
breaking through these areas only (Haplococcus) ; but 
Cystic phase of usua iiy the cyst-wall breaks down and liberates the 

Vampyrella. Ihe J J 

contents of the spores, or the spore escapes through any part of the 

cyst have divided , ' -T t i ii_ i 

into four equal membranes. In spore -formation the protoplasm 
three' are f visible! usually discharges all extraneous matters, and one 
(After Lankester large or a number of smaller granules of these 

and Cienkowski.) . i i?ri i 

ejecta are found between the wall of the cyst and 
that of the spores. There is no evidence at present that any 
process of conjugation occurs between the liberated zoospores, 
except in Ciliophrys (Cienkowski), and, in the absence of any 
systematic study of the nuclear substance of the spores, we are not 
in a position to state that the condition of the nuclei or nucleo- 
plasrn of the spores is in any way different to that of the other 
phases of life. There is therefore no justification whatever for 
the assumption that any form of cyst -formation indicates or is 
associated with a sexual process. 1 

A remarkable phenomenon has recently been described by de 
Bruyne in Leptophrys mllosa. After a period of feeding, the animal 
becomes spherical in shape 
and enters upon a period of 
rest. From the surface there 
are protruded a number of deli- 
cate filaments (Fig. 3) which 
terminate in hyaline globules. 
These globules are discharged 
and the filaments after some 
time are slowly withdrawn. 

When conditions are 
favourable there emerge 

from the Cyst One Or more Leptophrys vlllosa. A, a specimen actively feed- 
/T j. ing, showing, v, a large non - contractile vacuole ; 

(iUOnadineae aZOO- d, the diatoms on which it is feeding ; and t, a tuft 


Fio. 3. 

<vr rmo /- 

< p 

of pointed pseudopodia at the posterior end of the 
body. B, a resting stage of the same animal, pro- 


sporeae, j 

more flagellulae (Monadineae villed with filamentous processes, p, which discharge 
r-r e\ mi minute globules, s.p, of hyaline protoplasm. (After 
ZOOSpOreae, Zopf). Ihe deBruyne.) 

1 According to von Prowazek the nuclei of the spores of Plasmodiophora are 
formed by karyogamy (Arb. aus den kaiserl. Gesundheitsamte, xxii., 1905, p. 396). 


amoebulae either grow and become Actinophrys-like in form (l~am- 
pyrella) or unite to form plasmoclia (Leptopkrys, Endyomma, etc.). 

The flagellulae are provided usually with one, but sometimes 
two (Dtplophysalis, Gymnococcus) whip-like cilia, and sometimes also 
with a vacuole. They sometimes swim about actively and attack 
the organisms on which they feed (Cdpoddla, Fig. 8, A); but usually 
they soon withdraw their cilia and become amoeboid in shape, and 
the amoebulae thus formed either unite to form plasmodia or grow 
independently into the adult form. 

The classification of Proteomyxa has always presented innumer- 
able difficulties, and even at the present day our knowledge is so 
incomplete that nothing better than a tentative arrangement of the 
genera can be suggested. 

A large number of the genera were placed in a division 
(Monadineae) of the Mycetozoa (Pilzthiere) by Zopf, others are 
regarded as Foraminifera nuda by Ilhumbler, and Biitschli included 
several of the genera in the Heliozoa. 

Zopf further divided his genera into two groups, the Mona- 
dineae azoosporeae and the Monadineae zoosporeae. In the former 
the cysts give rise to amoebulae, and in the latter to flagellulae. 
It does not appear satisfactory, however, to use the characters 
of the swarm-spores alone as a basis of classification. Pseudospwa, 
with a flagellate zoospore, is clearly related to Vampyrella and 
its allies, which have an amoebulate zoospore ; and Enteromyxa,, 
Myxastrum, and other genera, with an amoebulate zoospore, appear 
to have no close relation to Vampyrella. 

FIG. 4. 

Monobia confluens. A number of individuals connected together by protoplasmic strands 
to form a loose meshwork colony. (After Schneider.) 

In attempting to classify the Proteomyxa, certain genera stand 
out as clearly related to other groups of Protozoa. Thus Monobia 
is closely related to the Heliozoa, Protogenes to the Foraminifera, 
Protamoeba and Gloidium to the Gymnamoebida, and Plasmodiophora 


to the Mycetozoa. Taking into consideration the form assumed by 
the pseudopodia, the habit of plasmodium- formation, as well as 
the character of the zoospores, most of the other genera can be 
arranged around these as central types. But there still remain 
some forms whose affinities are at present quite obscure, and these 
must be separated for the present into a group by themselves. 

The genera are here arranged in five groups according to their 
supposed affinities with the other orders of Protozoa. 


The following two genera appear to have affinities with the Gymna- 

Nothing whatever is known concerning their life-history, and it is 
probable they will prove to be but a stage in the life-history of an Amoeba. 

Protamoeba, Haeckel, is like an Amoeba, but without any definite 
nucleus or contractile vacuole. Freshwater and marine. 1 10 /x (Penard). 

Gloidium, Sorokin (Fig. 5), differs from Protamoeba in possessing a 
contractile vacuole. Occasionally the surface is denticulated. Fresh- 
water, 71 fj.. G. inquinatum, Penard, 385 p. The genus Gringa, Frenzel, 
is probably a species of Gloidium. 

FIG. 5. 

Four stages in the division of Gloidium qitadrifidum. c.v, contractile vacuoles. (After 


The genus Monobia in this group is closely related to Heliozoa. 
Monopodium and Vampyrella are closely related to one another, 
and agree with Vampyrellidium and Pseudospora in having a stage 
with delicate radiating pseudopodia like an Adinophrys. Leptophrys 
has affinities with Vampyrella, but differs from it in the shape of the 
body, which is irregular. Myxastrum is in some respects intermediate 
between the genera included in this group and those in Group D. 

(IV.) l Monobia, Schneider (Fig. 4). A number of Actinophrys-like 
individuals, but without nucleus or contractile vacuoles, and of a bluish 

1 As the genera included in the Proteomyxa in this volume have been shifted 
about from one class to another by different authors, the roman figures in brackets 
have been introduced to indicate to the reader the position assigned to each genus by 
the leading writers on Protozoology, when it differs from that given to the same genus 
iu the text. Thus the genera marked (I.) were referred to the Monadineae azoosporeae, 
(II.) to the Monadineae zoosporeae of the Mycetozoa by Zopf ; (III.) to the Foraminifera 
nuda by Rhumbler (22) ; (IV.) to the Heliozoa by Biitschli and Schaudinn. 


colour by transmitted light, are united into a colony by the fusion of the 
ends of their contiguous pseudopodia. Reproduction by fission has been 
observed, but no process of spore-formation is known. Freshwater. 

(I.), (IV.) Vampyrella, Cienkowski (Fig. 6, 5). Several species of 
this widely distributed genus are known. There is an Actinophrys stage 
in which, according to some authors, there is a nucleus. Vampyrella 
lateritia attacks Spirogyra by pushing a lobate pseudopodium into the 
cell and gradually absorbing its contents. V. gomphonematis attacks the 
stalked diatom Gomphonema, completely surrounding the frustules and 
absorbing their contents. Cysts are formed surrounded by a single 
smooth membrane, the animal discharges particles of undigested food 

FIG. 6. 

1, Protomyxa aurantiaca, Haeckel, plasmodium phase. The naked protoplasm shows branched, 
reticulate processes and numerous non-contractile filaments It is in the act of engulfing a 
Ceratium. Shells of engulfed Ciliata (Tintinnabula) are embedded deeply in the endoplasm, 
a. 2, cystic phase ot Pfotomyaea; <i, transparent cyst-wall; 6, protoplasm broken up into 
spores. 3, flagellula phase of Protomyxa. 4, amoebula phase of the same, the form assumed after 
a short period by the flajjellulae. 5, Vampyrella lateritia. Cienk. Actinophrys stage penetrating 
a cell of Spirogyra, b, by a process of its protoplasm, c, and taking up the substance of the Spiro- 
gyra cell, some of which is seen within the Vampyrella, a. 6, large individuals of Vampyrella 
.showing pseudopodia, e, and food-particles, a. (From Lankester, after Haeckel and Cienkowski.) 

materials and these are found with the shrunken protoplasm within the 
cyst- wall. Occasionally a second membrane is formed around the 
shrunken protoplasm. The protoplasm divides within the cyst-wall, and 
the nuclei of the spores thus formed are 2 p. in diameter and divide 
by karyokinesis. From the cyst there escape one, but usually four 
or five amoebulae, which soon develop radiate pseudopodia and float 
away in search of their food. In some species (e.g. V. gomphonematis) it 


seems certain that several individuals may fuse to form a plasmodium. 
No contractile vacuoles occur at any stage. The size varies consider- 
ably, 20-70 p.. They are nearly all freshwater forms, but one species, 
V. gomphonematis, is also marine. 

Monadopsis, Klein, is probably a species of Vampyrella. 

(I.) Vampyrellidium, Zopf. This genus is parasitic on freshwater 
Algae, particularly on Lingbya. Two kinds of cysts are formed, the 
zoocysts with a clear homogeneous membrane, and the hypnocysts with a 
thicker membrane. In other respects it is closely related to Vampyrella. A 
nucleus surrounded by a hyaline area is said (Zopf) to occur at every stage. 

(I.) Leptophrys, Hertwig and Lesser (Fig. 3), appears to be closely 
related to Vampyrella, but it forms larger vacuolated plasmodia by the 
fusion of the amoeboid zoospores. It is also characterised by the presence 
in the protoplasm of numerous paramylum granules. Like Vampyrella 
it is found parasitic on various freshwater lower Algae. It is either 
colourless or tinged with chlorophyll. The cysts are sometimes 0'25 mm. 
in diameter. They give rise to three or four amoeboid zoospores. No 
nuclei have been observed at any stage. 

(IV.) Monopodium (Haeckelina), Mereschkowsky, is an Actinophrys-like 
form with hyaline protoplasm and very delicate radiating pseudopodia 
attached to foreign bodies by a stalk. 0'2 mm. White Sea. Arclierina 
(see p. 33). 

(IV.) Nuclearia, Cienkowski (Fig. 8, E), also appears to be related to 
Vampyrella, but as a nucleus or nuclei and contractile vacuoles have been 
observed by several authors, it is perhaps more natural to regard it as a 
member of the order Heliozoa. 

(II.) Pseudospora, 1 Cienkowski, is a small Proteomyxan, 3-4 //,, which feeds 
upon Oedogonium, Spirogyra, etc. It is related to Gymnococcus and other 
members of Group C in producing flagellate zoospores. These zoospores, 
provided with one or two flagella and a minute nucleus, penetrate the 
bells of the host-plant and give rise to an Actinophrys-like stage, but 
they do not fuse to form a plasmodium. When they are fully fed the 
numerous pseudopodia are withdrawn and an amoeboid form is assumed 
previous to encystment (Fig. 8, B, C). Diplophysalis, Zopf, seems to be 
closely related to Pseudospora. 

(I.), (IV) Myxastrum, Haeckel, was found on the shores of the 
Canary Islands and is marine. It has a stage with numerous radiating 
pseudopodia, but forms plasmodia which attain to 0'5 mm. in diameter. 
The plasmodium encysts as a whole and the protoplasm forms 100 or 
more spores which give rise to amoeboid zoospores. 

(IV.) GiliophrySj Cienkowski (Fig. 8, G, H), probably belongs to this 
group. It is similar to Nuclearia in some respects, but at times it with- 
draws its radiating pseudopodia, becomes oval in shape, and swims rapidly 
by means of a long flagellum. Freshwater. 

In this group there is a stage when fine branching and anasto- 

_ J For Pseiidospora volcods, see Mastigophora, p. 168. 


niosing pseudopodia are formed and the affinities seem to be with the 
Foraminifera. Arachnula has some affinities with Nudearia and is re- 
garded as a Heliozoon by some authors. 

(III.) Protogenes, Haeckel (Fig. 7), is a small spherical organism 
with very numerous and delicate radiating and anastomosing pseudopodia 
Neither vacuoles nor nuclei have 
been observed. Marine. 

(III.) Biomyxa, Leidy, is a 
widespread genus occurring both 
in fresh and salt water. It 
passes though a spherical stage 
with radiating pseudopodia, but 
afterwards assumes a variety of 
.elongated or outstretched shapes 
with a few long, isolated, branch- 
ing and anastomosing pseudo- 
podia. One large or many small 
nuclei are said to occur (Rhum- 
bler). In B. vagans there are 
numerous minute contractile (?) 
vacuoles, but in B. (Gymnophrys) 
cometa there are none. It occurs 
in swampy sphagnum ground in 
this country. No definite nuclei 
have been observed and nothing 
is known concerning its life- 
history. The genera Gymnophrys, 
Cienkowski (Fig. 8, D), and 

Penardia, Cash, seem to be allied to Biomyxa. It has been suggested 
by Archer that Gymnophrys is but a detached portion of a Gromia, 
and West (27) has found it in a collection containing a large number 
of specimens of this Foraminifer. 

(III.) Arachnula, Cienkowski (Fig. 8, F), also is closely related to 
Biomyxa, but it forms long strands terminating in branching extremities 
provided with tufts of delicate anastomosing pseudopodia. Cysts have 
been described. It is found in fresh and brackish water. 

(III.) Pontomyxa, Topsent, is a form closely allied to Biomyxa and 
Penardia. The body assumes a variety of ribboned or dendritic forms, 
with numerous or interrupted groups of anastomosing pseudopodia. 
P. pallida from the Mediterranean Sea is colourless, but P. flava, like 
Penardia, is golden yellow in colour. P. flava was found in 35-50 
metres oft" the French coast and also in the Mediterranean Sea. The 
nuclei are said to be very small and reproduction occurs by multiple 

(III.) Rhizoplasma, Verworn (26). Spherical or sausage-shaped bodies 
of an orange-red colour, with numerous anastomosing pseudopodia, 5-10 
mm. in diameter when expanded, found in the Red Sea, are placed in 
this genus. There are 1-3 large transparent vesicular nuclei. The 
.coloured granules circulate in the pseudopodia. 

FIG. 7. 

Protogenes primordialis, Haeckel, from Schultze's 



(III.) Didyomyxa, Monticelli, is like the preceding genus, but with 
colourless pseudopodia. On Chaetomorplia crassa at Naples. 

Boderia, Wright (Fig. 9), is marine, orange or brown in colour, with 
a membranous investment (?), from openings in which protrude three to 
four long branching pseudopodia. The nucleus or nuclei after a time 

disappear, and the protoplasm spreads out in ragged masses on the slides. 
A number of naviculoid bodies are formed, from each of which a small 
amoebula emerges in a few days. Marine. 1-4 mm. 


Most of the genera included in this group form plasmodia, and their 
affinities seem to be with the Mycetozoa. No plasmodium-formation has 
been found in Aphelidium, Colpodella, Pseudosporidium, and Pseudamphi- 


monas. Zoospores with one or two flagella have been seen in all the 
genera except Myxodictyiim, Bursulla, and Tetramyxa. It is possible that 
Colpodella is related to the Mastigophora. 

(III.) Protomyxa (Fig. 6, 1) was found by Haeckel attached to the shells 
of Spirilla on the coast of the Canary Islands, in the form of orange-yellow 
flakes consisting of branching and reticular protoplasm nourishing itself 
by the ingestion of Diatoms and 
Peridiniae. This is a plasmodium 
formed by the union of several 
amoebulae. The plasmodium en- 
cysts and gives rise to numerous 
flagellulae or swarm-spores. The 
diameter of the cyst is '12-'2 mm. 
The flagellulae pass into an amoe- 
bula phase, and the amoebulae 
unite to form the plasmodium. 

Myxodictyum, Haeckel, consists 
of a number of protomyxa-like 
individuals united by their pseudo- 
podia to form colonies. It is 
pelagic in habit and was found by 
Haeckel at Algeciras in Spain. 

(II.) Gyinnococcus, Zopf, occurs 
in Cladophora, Diatoms, and 
spermum. It forms a plasmodium. 
When fully fed it gives rise to zoo- 
cysts, from which three to twelve 
biflagellate zoospores escape. 

(II.) Aphelidium, Zopf, lives in 

the cells of Colenchaeta and in macerations of plant tissues. Hypnocysts 
furnished with an operculum are formed. A nucleated zoospore with 
one flagellum has been found in A. lacerans (de Bruyne). 

(II.) Protomonas, Cienkowski, has biflagellate zoospores which become 
amoeboid and unite to form a plasmodium. Freshwater and marine. 

(II.) Colpodella, Cienkowski (Fig. 8, A), is possibly allied to Protomonas. 
The zoospores have only one flagellum, and attack Mastigophora before 
they become amoeboid. They do not, however, form plasmodia. 

(II.) Tetramyxa, Gobel, forms large galls on various water-plants, 
especially Buppia. 

(II.) Plasmodiophora, Woronin, is the cause of the disease of turnips 
known as " Fingers and Toes," or " Hanburies " (German, Herniekrank- 
heit). The spores are found in damp ground. Each spore gives rise to 
a minute nucleated amoeboid zoospore with a single flagellum. This 
penetrates into the cells of the root and loses its flagellum. It increases 
in size and the nuclei divide. After a time plasmodium-formation begins 
by the fusion of neighbouring amoebulae, and the tissues of the host-plant 
disintegrate. As soon as the plasmodium is formed the nuclei increase 
rapidly by karyokinesis, but according to Nawaschin (21) there is a period 

Botleria turneri. 

(After Wright.) 


when the plasmodia exhibit no trace of nuclei, the nuclear substance being 
apparently distributed throughout the whole plasmodium. Subsequently 
the plasmodium breaks up into a great number of minute spherical 
spores. 1 

Pseudamphimonas, de Bruyne, was found on Caulerpa at Naples. The 
zoospores are biflagellate and extremely amoeboid. They withdraw their 
flagellae, and two or three have been seen to fuse together to form a 

(I.) Bursulla, Sorokin, is found in horse-dung. A number of amoebulae 
with long pointed pseudopodia unite to form a plasmodium. The 
plasmodia contract and form either stalked cysts (51 /*,), the contents of 
which divide and emerge as eight amoebulae, or they give rise to naked 
spherical cysts with rosy contents and an outer cortex, from each of 
which a single stalked zoospore emerges. 


The affinities of the genera included in this group are quite 

(I.) Enteromyxa, Cienkowski, forms, by the fusion of amoeboid zoospores, 
long vermiform plasmodia (O'5-l mm.) with short tubercular pseudopodia. 
These break up into segments, which encyst and give rise to two or 
seldom more amoeboid zoospores. It feeds on Oscillatoria. 

(I.) Endyonema, Zopf, forms cylindrical cysts of considerable length in 
the threads of filamentous algae. Nuclei are said to occur previous to 

Ectobiella, de Bruyne (Fig. 1), was found in the form of a biflagel- 
late pyriform zoospore. It attacks Licmophora and other diatoms, with- 
draws the flagella and pushes a pseudopodium into the protoplasm of its 
prey. When the contents of the diatom are assimilated, the amoeboid 
organisms wander away and encyst. 

Haplococcus, Zopf, is found in the muscles of the pig. Two kinds of 
cysts are described by Zopf, the zoocysts (1 6-22 /x) and the hypnocysts 
(25-30 /A). The membrane surrounding the former is thinner in some 
places than elsewhere, and from them escape six to fifteen amoeboid 
spores. The further history of the hypnocysts has not been followed. 

Pseudosporidium, Zopf, was found by Brass in vegetable infusions. 
It is amoeboid in form, with short blunt pseudopodia, a nucleus, and a 
vacuole. The cysts give rise to numerous small flagellate zoospores. 

Schizogenes, Pouchet, was found in the haemocoel of freshwater Ostra- 
cods and Copepods. It consists of small plastids of hyaline protoplasm, 
01-'03 mm. without vacuoles or nucleus, of indefinite form, and devoid 
of pseudopodia. It divides into parts, which become new individuals. 

BathybiuSj Huxley, and Protobathybius, Bessels, are no longer regarded 
as living organisms. It seems probable that both forms represent a colloid 
precipitate of calcium sulphate thrown down by the action of alcohol on 
sea-water (Murray). 

1 See Note, p. 4. 



The following recent general works on Protozoology will be found useful to 
students : 

1. Braun. Animal Parasites of Man. Translated by F. V. Theobald. 1906. 

2. Biitschli, 0. Protozoa. Bronu's Klassen und Ordnungen des Thierreichs. 

3. Calkins, G. N. Protozoa. Columbia University Biol. Series. 1901. 

4. Cash, J. The British Freshwater Rhizopoda and Heliozoa, vol. i. Ray 

Society, 1905. 

5. Doflcin, F. Die Protozoen als Parasiten und Kraukheitserreger. Jena, 1901. 

6. Hartog, M. M. Protozoa. Cambridge Natural History, vol. i., 1906. 

7. Lamj, A. Lehrbuch der vergleichende Anatomic. Protozoa. 1901. 

8. Penard, E. Faune rhizopodique du bassin du Leman. 1902. 

The following refer particularly to Proteomyxa : 

9. Benedcn, E. van. Q. J. Micr. Sci. xi., 1871, p. 254. 

10. Brass. Biol. Studien, i., 1883-4, p. 70. (Pseudosporidium.) 

11. de Bruyne, C. Arch. Biol. x., 1890. (Ectobiella, etc.) 

12. Cienkowski. Arch. mikr. Anat., 1865, 1876. 

13. Dangeard, P. A. Le Botaniste, (2), 1890, p. 33, and (7), 1900, p. 131. 

14. Gobel. Flora, No. '28, 1884. (Tetramyxa.) 

15. Haeckel, E. Monogr. der Moneren. Jen. Zeits. iv., 1868. 

16. System. Phylog. der Protist. u. Pflanzen. Berlin, 1894. 

17. Ho'<genraad, II. K. Arch. Protist. viii., 1907. (Vampyrella.) 

18. Mereschkowsky. Arch. mikr. Anat. xvi., 1879. (Monopodium.) 

19. Monticelli. Boll. Soc. Napoli, xi., 1897. (Dictyomyxa.) 

20. Murray, J. P. R. Soc. London, xxiv., 1876. 

21. Nawaschin. Flora, 1899, p. 404. (Plasmodiophora.) 

22. Rhumbler, L. Arch. Protist. iii., 1904. 

23. Schneider, A. Arch. mikr. Anat. vii., 1878. (Monobia.) 

24. Sorokin. Ann. Sci. Nat. Bot. (6) iii., 1876; Morph. Jahrb. iv., 1878, 

( Gloidium. ) 

25. Topsent, E. Arch. Zool. Exper. (3) i., 1893. (Pontomyxa.} 

26. Verworn. Arch. ges. Physiol. Ixii., 1896. (Rhizoplasma.) 

27. West, G. S. J. Linn. Soc. Zool., 1901, xxviii. p. 308. 

28. - - I.e., 1903, xxix. p. 108. 

29. Woronin. Pringsheim's Jahrbiicher, xi. (Plasmodiophora.) 

30. Wright, S. Journ. Anat. Physiol. i., 1867. (Boderia.) 

31. Zojif, W. Handbuch der Botanik. Edited by A. Schenk. Bd. iii., pt. 2 r 


THE PEOTOZOA (continued) 


THE term Heliozoa is commonly used to include a number of 
Protozoa, generally inhabitants of fresh water, with few characters 
in common except the possession of straight, radial pseudopodia 
which rarely anastomose, and the absence of anything like a 
capsular membrane dividing a central portion of the body from a 

peripheral portion, such as is found 
among the Eadiolaria. The more 
highly specialised members of the 
group have a spheroidal body, which 
rarely exhibits amoeboid change of 
shape, divided into a more vacuolated 

FIG. 1. 

Actinosphaerium Eichhorni, Ehrb. A, a drawing 
of an individual as seen in optical section ; c.^i, a 
contractile vacuole previous to discharge of its 
contents ; c. v z , the position of a contractile vacuole 
that has just collapsed ; e.r, food-vacuole ; r, a 
rotifer in the act of being engulfed in a food-vacuole. 
B, a small portion of the ectoplasm of the same 
animal very much enlarged ; N, the nuclei ; ps, a 
pseudopodium ; ps.a, the axis of the pseudopodium. 
The axes of the pseudopodia have been recently 
traced farther into the ectoplasm than is shown in 
the figure and into closer relation with the nuclei. 
(After Leidy.) 

ectoplasm and a less vacuolated endo- 
plasm, the endoplasm containing one 
or many nuclei, and sometimes a per- 
manent centrosoma distinct from the 
nucleus. The pseudopodia are long, 
slender, and stiff, projecting radially 
from the surface of the body, and 
generally consisting of a cortex con- 
tinuous with the ectoplasm and an 

axis prolonged into the endoplasm (Fig. 1, ps). In Elaeorhanis, 
Nudearia (Fig. 8, E, p. 1 0), and some others that may be regarded as 
being on the border-line between the Heliozoa and Group B of the 

1 By the late Prof. W. F. R. Weldon, F.R.S., and Prof. S. J. Hickson, F.R.S. 



Proteomyxa (cf. p. 6), no axial rod to the pseudopodium has been 
discovered. A skeleton may be present or absent ; when present 
it is generally siliceous, though it may be in part chitinous (Adino- 
lophus), or composed of a jelly whose chemical composition is 
unknown (Heterophrys), or built up of foreign particles (Elaeorhanis), 

Hertwig and Lesser (7), in a memoir which established the 
main lines of the modern classification of the group, included only 
those higher forms whose characters have been indicated, giving a 
conception of the Heliozoa both logical and in many ways con- 
venient ; but such a treatment neglects a singularly perfect series 
of forms, the higher members of which, such as Nuclearia (Fig. 8, E, 
p. 10), closely resemble undoubted Heliozoa, while from these we 
may pass step by step to such forms as Monobia or Vampyrella 
(Figs. 4 ; 6 (5), pp. 4 and 7), which are probably more nearly allied 
to the Mycetozoa than to the typical Heliozoa. We have here, in 
fact, a case such as often occurs in which different types of structure 
and life-history are connected by a series of intermediate forms so 
gradual that any attempt to define the limits of either must fail. 
Under these circumstances, the limits assigned to one or other group 
in a descriptive classification depend merely on convenience ; the 
only point of importance is to frame the classification in such a way 
that it shall not disguise the real continuity of the forms described. 
For this reason, most modern writers, while recognising the great 
value of the conception formulated by Hertwig and Lesser, have so 
enlarged it as to include among the Heliozoa a number of transi- 
tional genera (p. 6). 

For the sake of convenience, the forms that are included in the 
Heliozoa in this article are those in which one or more definitely 
formed nuclei are present during the vegetative phases of life, 
together with those genera which seem to have the closest zoological 
relation to them although their nuclei are not known. The 
genera that are sometimes classified with the Heliozoa, mainly on 
the ground that they have stiff radiating pseudopodia, but which 
afford some reasons for believing that their nuclei are dissipated 
during the vegetative phases of life, are placed with the Proteomyxa 
(see p. 6). 

It will be convenient to consider first the structure of the more 
highly specialised forms to which Hertwig and Lesser proposed 
that the name Heliozoa should be restricted, and to discuss the 
transitional genera afterwards. 

The characters of the more specialised Heliozoa may be illustrated 
by describing Adinophrys sol, the common freshwater species already 
mentioned. The body is spheroidal and minute, rarely exceeding 
0'05 mm. in diameter ; in a healthy undisturbed individual numerous 
stiff pseudopodia, each considerably longer than the diameter of the 
body, radiate from the surface. The body itself is divided into a 


clearer coarsely vacuolated ectoplasm, and a less transparent spongy 
or feebly vacuolated endoplasm, containing a centrally placed nucleus 
(Fig. 2(1), d). The ectoplasm is normally so crowded with vacuoles 
that it is reduced to a mere system of septa, and to a thin layer form- 
ing the cortex of the radial pseudopodia. During the ingestion of 
food, however, an aggregation of ectoplasm takes place, forming a 
short, blunt amoeboid projection by which the food is engulfed, and 
in which a digestive food-vacuole is formed (Fig. 2(1), a). The ecto- 
plasm usually contains a number of bright, highly refringent granules, 
remarkably uniform in diameter, which are carried from one region 
to another by streaming movements of the protoplasm ; thus they 
may often be seen streaming to or from the apex of a radial pseudo- 
podium, or towards the apex on one side and away from it on the 
other. The number of these granules is said to increase with 
increased nutrition, but their chemical nature is quite unknown. 

FIG. 2. 

1, Actinophrys sol, Ehrb., x 800; o, food-particle lying in a large food-vacuole; 6, deep- 
lyiii^' finely granular protoplasm ; c, axial filament of a pseudopodium extended inwards to the 
nucleus ; d, the centrally placed nucleus ; e, contractile vacuole ; /, superficial, much-vacuolated 
protoplasm. 2, Clathrulina elegans, Cienk., x 200. 3, Heterophrysmyriopoda, H. and L., x 660 ; 
a, nucleus ; 6, clearer protoplasm surrounding the nucleus ; e, the peculiar felted envelope. 
4, Rhaphidiophrys pallida, V. E. Schultze, x 430 ; a, food-particle ; b, a contractile vacuole (?), 
the nucleus is probably represented by the circular shaded body lying below 6 ; c, a food-particle ; 
rf, the centrosome. The tangentially disposed spicules are seen arranged in masses at the 
surface. 5, Acanthocystis turfacea, Carter, x 240 ; a, probably the centrosome ; b, clear pro- 
toplasm around the centrosome ; c, more superficial protoplasm with vacuoles and xanthellae ; 
d, coarser siliceous spicules ; e, finer forked siliceous spicules ; /, finely granular layer of 
protoplasm. The long pseudopodia stretching beyond the spicules are not lettered. 6, biflagellate 
"flagellula" of Acanthocystis acideata; a, nucleus. 7, Flagellula of Clathrulina elegans; , 
nucleus ; b, granules of uncertain composition. 8, Astrodisculus radians, Green , x 320 ; o, red- 
coloured fatty globule ; 6, peripheral homogeneous envelope. (From Lankester, after various 

The endoplasm is rarely vacuolated, and the bright refringent 
granules are absent from it. 

In a normal pseudopodium we can distinguish (1) a cortical 
layer, and (2) an axial filament. The cortical layer is continuous 
with the general ectoplasm at the base of each pseudopodium ; it is 
irregular in thickness, and may by a streaming movement become 
aggregated into amoeboid droplets of relatively large size during 
the seizure of prey (Fig. 2 (3)). The effect produced upon infusoria, 
small rotifers, and other ciliated organisms by contact with the 
pseudopodia is a marked paralysis, which has led many observers, 
from Ehrenberg onwards, to assume that some poisonous substance 
is formed by or contained in the cortex; but direct chemical 
evidence of this is wanting. The axial filament is a clear homo- 
geneous thread, which runs from the apex of a pseudopodium 
through the substance of the body, to end in a central dilatation in 
contact with the nuclear membrane. When a pseudopodium is 
withdrawn, its axial filament disappears, and cannot be demon- 
strated by staining reagents ; in the living animal it is more easily 


seen at some periods than at others, and may even for a time dis- 
appear without retraction of the pseudopodium. 

The nucleus is relatively large, with an obvious, doubly -con- 
toured membrane. Within the membrane is a fine reticulum of 
" linin " threads, on which are small particles of chromatin ; there 
is generally also a single large extra-reticular mass of chromatin, 
forming a karyosomatic "nucleolus." 

The vacuoles are of three kinds : non-contractile and contractile 
vacuoles which do not contain food-particles, together with diges- 
tive vacuoles which contain food. The non- contractile vacuoles 
form a layer occupying the whole thickness of the ectoplasm ; they 
contain a clear, colourless fluid, in which refringent granules, like 
those found in the ectoplasm, may often be seen floating, the number 
of such granules in a single vacuole being sometimes large. A 
non-contractile vacuole, which contains many granules, sometimes 
bursts, and the granules are scattered in the surrounding water. 
There is generally only one contractile vacuole, which rhythmically 
changes, enlarging slowly until its diameter may be about half that 
of the body, and then suddenly collapsing ; the cycle of dilatation 
and contraction is completed, at ordinary temperatures, in about 
one minute (40-100 seconds, Penard [14]). The function of the 
contractile vacuole is as obscure in this as in other cases. Most 
observers believe that the fluid, collected during dilatation, is 
expelled from the body during contraction of the vacuole, so that 
the whole process is excretory in nature ; but while it is difficult to 
watch an Adinophrys without sharing this opinion, it is equally 
difficult to demonstrate its truth. The contraction takes place so 
quickly that it is impossible to be sure whether a rupture of the body- 
wall occurs or not ; and all attempts to show that the collapse of 
the vacuole is accompanied by a disturbance in the surrounding 
water, such as would result from the forcible expulsion of its con- 
tents, have hitherto failed. 

Food-vacuoles are formed in the blunt processes of the ectoplasm 
already described. When fully formed they contain a clear fluid, 
surrounding the ingested food-mass, which doubtless contains some 
solvent in solution, analogous to those demonstrated in the similar 
vacuoles of amoebae and of ciliata. Formed immediately beneath 
the surface of the body, the food -vacuole remains throughout 
its whole existence in the ectoplasm, where the processes of diges- 
tion and absorption are completed ; a vacuole with a large food- 
mass may, however, travel into the deeper parts of the ectoplasm. 
After digestion is completed the residue of the food -mass remains 
in the vacuole for some time, being ultimately discharged by the 
bursting of the vacuole at some part of the surface of the body. 

The food consists of living organisms, animals and plants. 
Smaller prey is seized by the blunt ingestive processes alone, with- 


out help from the radial pseudopodia ; a larger creature is seized by 
a group of radial pseudopodia, which converge round it, generally 
(always ?) losing their axial filaments, and send out amoeboid 
processes, which more or less completely engulf the prey. The 
mass formed by these fused processes and the organism they con- 
tain travels towards the body, where it meets and fuses with an 
ingestive process. 

Actinoplirys is capable of performing various rolling or creeping 
movements on the bottom of the pond, but the creature spends 
much of its time suspended in the water, where it has a certain 
power of rising and of sinking, though the way in which this is 
effected is altogether obscure. 

At intervals Adinophrys may withdraw its pseudopodia, the 
axial filaments of which disappear ; it may then secrete a complex 
cyst of two layers an outer, fairly thick transparent layer of gela- 
tinous consistence, within which is a second, thinner layer. ' After 
the formation of these layers, the vacuoles disappear, the contractile 
vacuole being the last to go, and the whole body shrinks. The 
nucleus now divides mitotically (cf. infra, pp. 25-27), and the cyst 
divides into two, each of which becomes spherical. Within each 
of the resulting cysts a third hard, opaque membrane is secreted, 
and a period of quiescence ensues, after which the walls are ruptured 
and the creature emerges, new pseudopodia being rapidly formed. 
This account is based on that given by Schaudinn (17), who says 
that each daughter- cyst may divide again before entering on a 
period of quiescence ; on the other hand, many observers describe 
a process of encystment which is not accompanied by any division 

Just as encystment may occur without fission, so fission may, 
according to Schaudinn, occur without encystment. An individual 
about to divide in this way withdraws its pseudopodia, and a 
peculiar mitosis takes place, not accompanied by disappearance of 
the nuclear membrane or by the formation of centrosomata (infra, 
p. 28) ; this is followed by fission of the cell-body, and pseudo- 
podia are shortly afterwards emitted. 

The processes of fission just described, whether accompanied by 
encystment or not, are asexual, since there is no previous fusion 
of individuals or of nuclei. A process of plastogamic fusion, involv- 
ing the union of a number of individuals (as a rule by the ectoplasm 
only), without nuclear fusion, frequently occurs. The number 
of individuals so united is frequently two; but it may be over 
thirty (Schaudinn). Plastogamic individuals lose their pseudo- 
podia on the surfaces by which they are attached to each other 
but retain them elsewhere, and the union is not necessarily followed 
by a period of quiescence. Individuals which have been united in 
Jbhis way for some time may separate without withdrawing those 


pseudopodia which they retained during the plastogamy. Schaudinn 
thinks it probable that all recorded cases of division without mitosis 
and without retraction of the pseudopodia are really cases in which 
plastogamic individuals have been seen to separate. 

An observation recently made by Calkins on Paramecium suggests 
a possible eft'ect of plastogamy. The work of Maupas has shown 
that, after a certain number of asexual divisions, Paramecium and 
other Ciliata, when grown in artificial culture-media with a constant 
supply of food of one kind, exhibit phenomena of degeneration, 
which quickly lead to the death of the whole culture, unless 
individuals produced by another zygote are introduced. If such 
individuals are introduced, plastogamy occurs, which is quickly 
followed by a complicated sexual (karyogamic) process ; and after 
this the "rejuvenated" culture can enter upon another period of 
asexual multiplication (cf. Chap. I. Fasc. II. pp. 386, 387). Calkins 
has, however, shown that a culture which exhibits signs of degenera- 
tion may be completely "rejuvenated" by purely chemical stimuli, 
such as an appropriate change of food, and that if plastogamy alone 
be allowed to occur, the conjugating individuals being shaken apart 
before the nuclear changes which precede karyogamy have taken 
place, these individuals can still go through a further cycle of 
asexual divisions. Nothing analogous to the phenomena of 
"senile degeneration" described by Maupas has been observed 
among the Heliozoa, but it is possible that it may occur, and that 
the rejuvenescent effect of natural plastogamy is similar to that of 
the artificial plastogamy observed by Calkins. 

Although plastogamy is often followed by a complete separation 
of individuals, it may be the beginning of a sexual karyogamic 
process, which has been carefully studied by Schaudinn. In this 
case the mass of individuals, united by ectosarc, sinks to the bottom 
of the water; the pseudopodia are withdrawn, and a common 
gelatinous cyst is secreted, like the outer layer of a solitary cyst. 
Each individual within the gelatinous common cyst secretes a 
membrane, which is thrown into wrinkles, so that in optical 
section it looks as if made of spicules joined together. These 
cysts lie in pairs within the common jelly, the two members of a 
pair in contact (Fig. 3). The nucleus of each cyst now goes 
through a mitosis (infra, pp. 25, 27), which results in the extrusion 
of a single polar body. When the pronuclei of a pair of adjacent 
cysts have returned to the resting condition, the walls of the cysts 
break down at the point of contact, the two cell-bodies fuse, their 
pronuclei also fusing, and the completed zygote becomes spheroidal 
within the membrane derived from the cyst -walls of the two 
gametes. After a period of quiescence the nucleus of the zygote 
divides into two, by a process identical with that observed in 
asexual cysts, and the division of the nucleus is followed by that 



of the cell-body and of the cyst-wall. On emerging from the cyst, 
after division, vacuoles and psetidopodia are developed, and the 
adult condition is assumed. 

The majority of the higher Heliozoa resemble Adinophrys in 
general structure, though their appearance may be greatly altered 
by the presence of a skeleton or by the formation of a stalk. 

The modifications of the cell-body are chiefly those connected with 
the greater or less development of vacuoles and of various coloured 
substances. The division into ectoplasm and endoplasm is generally 
obvious. The ectoplasm usually contains contractile vacuoles, which 


Adinophrys sol. I, two free-swimming individuals in conjugation. II, the same individuals 
in an early phase of encystment. The nuclei are considerably enlarged. Ill, formation of 
the polar spindles. IV, stage with two reduced nuclei and degenerating polar nuclei. V, 
the reduced nuclei have fused together and the polar nuclei have reached the periphery. 
VI, the first segmentation spindle is formed and the polar nuclei are ejected as polar bodies. 
i/-, cyst membrane; e.v, contractile vacuoles; N, nuclei; P.N, polar nuclei; P.B, polar 
bodies ; P.Sp, polar spindle ; S.Sp, segmentation spindle. (After Schaudinn.) 

may be very numerous (more than 20 in Acanthocystis). In 
Actinosphaerium the system of non-contractile vacuoles is even more 
highly developed than in Adinophrys, but in the skeletogenous genera 
the non-contractile vacuoles are few. The ectoplasm is usually the 
seat of digestion and assimilation, as it is in Adinophrys ; and usually 
contains refringent granules, which may be rounded, like those of 
Adinophrys, or crystalloid (Heteropkrys). Perhaps the larger coloured 
granules which occur either in the ectoplasm or in the endoplasm, or 
scattered throughout the body, belong to a different category from 
the refringent granules ; large brown granules may occur in the 
ectoplasm (Pinacocystis), brownish or yellowish bodies may be scattered 


through the whole substance of the body (Pompholyxophrys, Rliaphi- 
diophrys), and in a few forms (Elaeorhanis) a large coloured oil 
globule is found in the endoplasm. In Actinosphaerium, where 
digestion and assimilation occur in the endoplasm, that region of the 
body is crowded with brownish refringent granules, leaving the ecto- 
plasm relatively free. A few of the larger coloured droplets have 
been described as fatty ; but the chemical nature of most of these 
coloured bodies is quite unknown. 

Chlorophyll associated with differentiated chloroplasts is found 
either in the endoplasm (some varieties of Actinosphaerium Eichhornii) 
or in the ectoplasm (Rhaphidiophrys, Heterophrys, etc.). The nature and 
origin of these bodies have been much debated ; some writers have 
regarded them as the remains of green animals or plants ingested 
as food ; Archer and Greeff maintained that they were in many 
cases, at least, formed by the Heliozoa in which they were observed. 
There can be little doubt, however, that they are in some cases at 
least of the same nature as the Xanthellae that occur in Radiolaria 
(see p. 97) and in Trichosphaerium among the Lobosa, and that 
they are therefore independent organisms living in association with 
the Heliozoa, and are not, as has been suggested, of endogenous origin. 
Although we have at present very little information concerning the 
history of these organisms in the Heliozoa, the observations of 
Penard on green varieties of Actinosphaerium lend strong support 
to this suggestion. This author found that the green cells are oval 
in shape, 7-10 //, in length, and surrounded by a clear gelatinous 
membrane. They possess a bell-shaped chromatophore, a spherical 
pyrenoid, and in some cases a vacuole at one end. On crushing 
the Actinosphaerium, these cells escape, and subsequently protrude 
first one and then a second very delicate flagellum. He believes 
the organism to be identical with the Palmellacean Alga Sphaero- 
cystis Schroteri (Chodat). In other cases he has seen a large number 
of flagellate organisms belonging to the genus Chlamydomonas 
attached to the surface of an Actinosphaerium, and has shown that 
they are actively attracted to the host. It is true that at present 
it has not been proved that the Chlamydonionads actually enter the 
ectoplasm of the Actinosphaerium and become the xanthellae ; but in 
view of the proof recently published by Keeble and Gamble (10), 
that the infecting organism of the Turbellarian Convoluta belongs to 
the Chlamydomonadina, Penard's observation is very suggestive. 
Awerinzew (1) has recently described the xanthella of Actino- 
sphaerium as Zoochlorella actinosphaerii. 

In addition to the xanthellae, other organisms are occasionally 
found in the ectoplasm of the Heliozoa. Thus, a eiliate infusorian 
allied to the genus Blepharisma has been found in as many as 
30 per cent of the individuals of Rhaphidiophrys viridis found at 
Bernex, and a rotifer attributed to the genus Monolabis by Archer 


and to the genus Proales by Penard occurs in the ectoplasm of 
Acanthocystis turfacca. It is probable also that the minute rods 
that have been found in Acanthocystis turfacea (Leidy) and the 
corpuscles in A. spinifera, Rhaphidiophrys viridis, and Heterophrys 
myriopoda may be bacteria. 

The structure of the pseudopodia is probably very constant in all 
the higher forms. In Elaeorhanis, Nudearia, and Hedriocystis there 
appears to be no axial filament. In Clathrulina elegans and in 
Elaeorlumis they are sometimes bifurcated. In a Heliozoon allied 
to Adinophrys, Crawley (5) has recently observed that the pseudo- 
podia are arranged in tufts at the periphery, and may either 
remain stiff and motionless like the typical pseudopodia of Heliozoa 
or assume lashing movements like flagella or cilia. In Adino- 
Sj'hacrium arachnoid-eum, Penard, the pseudopodia are very long, 
branching, and capable of anastomoses. 

The relation of the inner ends of the axial filaments of the 
typical pseudopodia varies in a remarkable way with variation in 
the position of the nucleus. In Actinosphaerium, where the 
number of nuclei is very great (sometimes over 400), the axial 
fibres end each in the neighbourhood of a nucleus, if not in actual 
contact with its membrane, so that the relation is here similar to 
that of Adinophrys. In a great number of genera, however, the 
centre of the body is occupied by a deeply-staining granule first 
discovered by Grenacher (6) and now known to behave like a 
centrosome ; to this body the inner ends of the axial filaments are 
attached (Fig. 6, A). There is never more than a single centrosome, 
which may be associated with a single eccentrically-placed nucleus 
(Acanthocystis, etc.) or with many nuclei (Gymnosphaera). 

Skeletal investments of several kinds are found among the higher 
Heliozoa. In Elaeorhanis the body is covered by an agglutina- 
tion of diatoms, sand-grains, etc., loosely cemented together ; in 
Heterophrys (Fig. 2 (3)) the body is surroupded by a finely granular, 
transparent capsule, of gelatinous consistency and quite unknown 
composition, soluble in strong acids ; this capsule is separated from 
the ectoplasm by a considerable space, traversed only by the radial 
pseudopodia, which emerge through perforations in its substance. 
The outer surface of the capsule bears delicate radial spines, shorter 
than the pseudopodia, which are regarded by Penard as being 
chitinous in composition on the ground that they are soluble in 
boiling sulphuric acid. In Actinolophus the greater part of the 
body is naked, except for a short time before encystment ; but the 
stalk, on which the body rests, is a tube of what appears to be 
chitin, containing one or two thread-like prolongations of the body. 
The greater number of skeletons are, however, siliceous, the silica 
being deposited in the form of separate or loosely-articulated plates 
or spicules (Chalarothoraca) or as a continuous basketwork (Desmo- 


thoraca). In the Chalarothoraca the siliceous particles may be 
minute and spherical, lying close together and forming one or 
several layers (Pompholyxophrys), or they may be elongated spicules, 
or flattened plates. Spicules are of two kinds, the one kind curved 
and pointed at each end, the other straight, pointed or bifurcate at 
one end, flattened and expanded at the other. The curved spicules 
are placed tangentially to the surface of the body, and may be the 
only skeletal elements present (Ithaphidiophrys), in which case they 
form a loose investment for the animal, from which groups of 
spicules are occasionally carried up the pseudopodia by the 

FIG. 4. 

Heterophrys Fockei, Archer, c.c, contractile vacuoles. A nucleus is present in the centre 
of the protoplasm, but is not'shown in the figure, s, radial chitinous (?) spines surrounding 
the envelope. Several xanthellae are seen in the protoplasm. (After Hertwig and Lesser.) 

streaming movement of the ectosarc (Fig. 2 (4)). In lihaphidocystis 
some very remarkable funnel-shaped or wine-glass-shaped spicules 
are found. In Acanthocystis both tangential scales and straight 
spicules may be present, the latter being radially placed, with their 
pointed ends outwards. There may be two kinds of these radial 
spicules, a longer hollow kind with the free extremity bluntly 
pointed, and a shorter solid kind with the free end forked (Fig. 2 (5)). 
Siliceous plates, articulated together by their edges to form a 
capsule round the body, occur in Pinacocystis and in Pinaciophora. 
In Pinacocystis the pseudopodia emerge through the spaces between 
the plates, but in Pinaciophora, according to Greeff, the plates are 
perforated by fine pores. 


In the Desmothoraca, of which Clathrulina is the best-known 
genus, the skeleton has the form of a spherical basketwork, the 
bars of which often show a median ridge on the outer surface, the 
spaces between the bars being irregularly polygonal with rounded 
angles (Fig. 2 (2)). This basketwork is supported on a long, hollow 
.siliceous stalk. 

The structure of the nucleus and the processes of hiryolcinesis 
have been minutely described by R. Hertwig (8) in Actinosphaerium, 
and his descriptions are in accord with what is known concerning 
them in the higher Heliozoa generally. 

The resting nucleus of Actinosphaerium has a definite membrane 
.continuous with an internal achromatic network whose relation to 
the chromatin elements is very variable. The whole of the 
.chromatin may be collected into a relatively large mass, supported 
in a matrix of achromatic substance ("plastin") and forming a 
conspicuous " karyosomatic " nucleolus ; such a condition of the 
nucleus may be induced by starvation, or it may appear as a pre- 
liminary to division. In well-fed individuals the chromatin spreads 
through the nucleus in the form of coarse branches or networks. 

Nuclear division may be direct, in the formation of buds or 
swarm -spores, or by karyokinesis. Karyokinesis occurs in the 
division of the nuclei within the body of the multinucleate forms 
(e.g. Actinosphaerium) without being followed by division of the 
body ; in forms with a single nucleus it occurs during fission, and 
during the maturation of the conjugants (gametocytes). 

In Actinosphaerium there are three kinds of karyokinesis, that 
differ from each other in some details of considerable theoretical 
importance. In the nuclear divisions of the unencysted body no 
entrosomes are formed, and the spindle is considerably compressed 
between the two poles. In both the mitoses of the maturation of the 
gametocytes, centrosomes occur at each pole of the spindle, but in 
the first (polar) division the chromosomes are larger than in the second 
.(polar) division, and there are some other differences in detail of 
minor importance. In all three kinds of karyokinesis there are 
numerous chromosomes (about 150), and both the divisions of the 
nuclei in the maturation of the gametocytes are of the nature of "equa- 
tion " divisions, the number of the chromosomes not being reduced. 

It may be convenient to describe in greater detail the second 
polar division of Actinosphaerium as an example of the karyokinesis 
of the Heliozoan nucleus. At the end of the first polar division, 
one of the resultant nuclei degenerates and is ultimately ejected 
with the first polar body, the other remains in the centre of the 
protoplasm and passes through a short period of rest. At one 
pole of this resting nucleus there is a clearly-marked centrosome 
surrounded by a small aster. Antecedent to the second polar 
division the centrosome diminishes in size (Fig. 5, I, c), and 



subsequently divides into two parts, which travel to opposite poles 
of the nucleus. The nucleus now begins to increase considerably 
in size, and is seen to contain several large chromatin bodies which 
certainly contain both chromatin and plastin derived from the 
nucleoli (Fig. 5, II). The centrosomes at each pole of the 
nucleolus are of considerable size and more conspicuous than at 
any other time in the divisions of the three kinds of karyokinesis. 
The chromosomes are now formed by a breaking down of the 

@\. . 



~" -~^ c 


*V:-:- *t~3:i.i.1il 

FIG. 5. 

Actinosphaeriitm. Formation of the second polar spindle. I, the nucleus after the first 
polar division, the centrosome (c) reduced in size previous to the formation of the second 
polar figure. II, the same nucleus at a later stage with two centrosomes. Ill, IV, V, VI, 
VII, stages in the formation of the second polar nucleus. (After R. Hertwig.) 

chromatin masses, and gradually assume an equatorial position. 
They are at first very irregular and angular in shape, but ultimately 
become rod-shaped, constrict in the middle, and divide transversely. 
The spindle fibres seem to be formed from the achromatic network, 
and several plastin remnants remain in the nucleus during ther 
formation of the chromosomes. The chromosomes now travel 
towards the opposite poles of the spindle in the usual way 
(Fig. 5, VI), and subsequently become arranged in a fan-shaped 
manner at the extremities of the now elongated spindle. According 



to Hertwig (8) the chromosomes of the second polar division are 
only half the size of the chromosomes of the first division, and 
there is, therefore, a reduction in the mass of the 'chromosomes, 
although there is apparently no reduction in their number. 

The karyokinesis of the nuclei of the ordinary unencysted 
Adinospliaerium differs from that just described principally in the 
fact that no centrosomes are present. The first sign of commencing 
division in these nuclei is the accumulation of a clear mass of 
nearly homogeneous protoplasm at each pole ; the nucleus becomes 



Fio. 6. 

A, Acanthocystis aculeata, H. and L., in the living condition, with expanded pseudopodia. 
N, the nucleus ; c, the centrosome. B, C, D, B, F, successive stages in the mitoticldivision of 
the nucleus as seen in preparations. (After Schaudinn.) 

flattened so that the diameter which passes through the proto- 
plasmic masses is the shortest, and at each end of this diameter an 
accumulation of achromatic nuclear substance is formed, giving rise 
to what Hertwig calls the " polar plates." 

In Acanthocystis the nucleus is situated excentrically, and con- 
sists of a central deeply -staining body, the " pseudonucleolus," 
surrounded by an area which certainly contains a linin network 
but much less chromatin. At the exact centre of the endoplasm 
there is a small body which exhibits radiating lines which 
appear to extend outwards and be continuous Avith the axes 
of the pseudopodia (Fig. 6). This body, originally described by 



Grenadier (6) as the " Centralkorn," has been proved by 
Schaudinn to be a true centrosome. It has been discovered to 
be a permanent of the body in llhaphidiophrys, Adinolophus, Hetero- 
phrys, and Sphaerastrum. Before division of the nucleus it divides 
into two equal parts, which take a position at opposite poles of the 
endoplasm, each one surrounded by an aster of radiating lines. The 
nucleus leaves its excentric position and becomes situated in a 
direct line between the two centrosomes. The nuclear mem- 
brane then fades away and a party of numerous small chromo- 
somes occupy a position of an equatorial band on the spindle that 

Fio. 7. 

A, B, C, direct amitotic division of the nucleus of Acanthocystis aculeata as seen in the 
process of the formation of buds. U, a colony of Acanthocystis formed by the gemmation of 
a single individual. Only two individuals of the colony exhibit a centrosome, and these have 
been formed by division, with nuclear mitosis, of the primary individuals ; the others have 
been formed by gemmation without nuclear mitosis. E, a single bud freed from the 
colony. F, a flagellula. G, an amoeboid spore. (After Schaudinn.) 

is formed from the linin of the nucleus. The subsequent phases 
of the nuclear division resemble those of the typical karyokinesis 
of the metazoan cell. 

* In the formation of the buds of Acantlwcystis the nucleus divides 
directly and the centrosome remains unchanged (Fig. 7, A, B). 
The buds are therefore for a time without any centrosome, but 
this body is formed afresh in the buds from the nucleus. (See 
Part I. Fasc. II. Fig. 20, p. 41.) 

Reproductive Processes. Probably all the higher Heliozoa are 
capable of fission, preceded or not by encystment, although the 
process has not been observed in all. The division of the nucleus 


is mitotic, and is probably of the type observed in adult Actino- 
spliaerium or of that seen in Acanthocystis, according to the presence 
or absence of a permanent centrosome. 

Budding has been observed in several cases ; and the process 
has lately been described in detail by Schaudinn (19) in Acantho- 
cystis. The nucleus divides directly once or several times, so that 
the body may contain a considerable number of nuclei ; during 
this process the pseudopodia are not withdrawn, the centrosome 
and the system of axial filaments remaining unchanged. One of 
the nuclei resulting from this division remains in the body of the 
parent without further change ; each of the others travels into a 
small projection from the surface of the body, which is the future 
bud. Every bud is covered with a layer of spicules derived from 
the parental skeleton, but it contains no centrosome, nor any trace 
of radial fibres. The buds so formed may behave very differently 
in different cases, and there is at present no knowledge of the 
circumstances which determine their behaviour. A bud may 
separate from the parent in the condition described, and may 
divide one or more times, the products of division going through a 
short resting stage before emitting pseudopodia ; or the resting 
stage may occur immediately after the bud leaves the parent, in 
which case it does not divide before assuming the adult condition. 
In these cases there is nothing like " spore-formation " ; but a bud 
may become amoeboid, and creep out of its skeletal investment, 
either before the skeleton has separated from the parent or 
immediately afterwards ; and such an amoebula may creep about 
for a day or two, by means of blunt pseudopodia, before it becomes 
spherical and secretes new spicules ; or, division of the nucleus may 
occur within the bud, so that several amoebulae leave it, instead of 
one. Lastly, an amoebula, at the moment of leaving the parental 
skeleton or soon afterwards, may develop two flagella, by means of 
which it swims for a short time ; such " flagellulae " quickly 
become amoeboid and creep about for a further period as amoe- 
bulae, before becoming spherical. None of these buds or spores are 
known to conjugate, and indeed the origin of sexual spores by an 
amitotic division would be remarkable ; but, however they behave in 
the meantime, about the fourth or fifth day after emission each of 
them becomes spheroidal, and secretes a skeleton of small tangential 
spicules, which are first formed in the immediate neighbourhood of 
the nucleus, and afterwards travel to the periphery. The centro- 
some arises from the nucleus (Part I. Fasc. II. Fig. 20, p. 41), and 
after it is established the axes of the radial pseudopodia appear. 

The formation of "swarm -spores" was first described by 
Cienkowski (4) in Clathrulina ; it was more recently discovered by 
Schaudinn (19) in Acanthocystis ; and it may occur in Adinophrys 


Sexual (karyogamic) processes have only been observed in 
Actinophrys and in Actinosphaerium ; the process in Actinophrys 
has already been described ; the phenomena observed in Actino- 

Actinosphaerium. A, a mother-cyst just before it breaks up into primary cysts. The 
nuclei are considerably reduced in number and the protoplasm contains numerous small 
oval yolk-plates, y.p. B, the primary cysts have each divided into two secondary cysts. The 
sister-cyst of a is not seen in the figure. N, nuclei ; c.m, mother-cyst membrane ; c.m%, cyst 
membrane of the first order. (After Brauer.) 

sphaerium are in many ways remarkably different. The first indica- 
tion of approaching karyogamy is the encystment of a single 
individual. The pseudopodia are withdrawn, their axial filaments 


are absorbed, and the animal sinks to the bottom of the water, 
where it exhibits considerable amoeboid movement, sometimes 
giving out slender pointed pseudopodia which have no axial 
filaments ; food-particles are ejected, and a thick, transparent cyst 
is formed. This " mother-cyst " is of gelatinous consistence, sticky 
on the outside, and its substance is deposited in concentric layers. 
The peripheral vacuoles disappear after encystment, and numerous 
peculiar oval discs, probably consisting of reserve food- material, 
appear; these bodies may be called "yolk-plates" (Hertwig). 
While the yolk -plates are forming, the number of the nuclei 
diminishes, until not more than one -twentieth of the original 
number remain. The process by which this reduction is effected 
is not quite clear; Schneider and more recently Brauer (2) 
have described a fusion of nuclei during the reduction; and 
Brauer's figures of this fusion are very convincing ; Hertwig, 
although he considers it not improbable that such a fusion occurs, 
has never been able to demonstrate it. When the reduction in the 
number of nuclei is completed, the body divides into as many 
pieces as there are nuclei, each piece containing a single nucleus. 
Every result of this division is enclosed in a siliceous " primary 
cyst," largely formed by rearrangement of scattered spicules 
secreted before division. The number of primary cysts varies 
from one to thirty-five ; and Smith (20) has recently shown 
that there is an interesting relation between the number formed 
and the temperature at which encystment occurs ; at high tempera- 
tures the number is smaller and the cysts are larger ; at low 
temperatures the number of cysts is greater and their diameter 
less. Smith also shows that the quantity of chromatin contained 
in the nuclei of primary cysts formed at a low temperature is 
greater than that found in cysts formed at higher temperatures. 
Shortly after its formation, each primary cyst divides into two; 
the nucleus behaves in essentially the same way as dividing nuclei in 
the unencysted form (cf. p. 25) ; the number of chromosomes is very 
large, and is estimated by Hertwig at from 130 to 150. The 
secondary cysts, formed by the division of each primary cyst, now 
behave like gametocytes ; a centrosome is extruded from the 
nucleus, and a nuclear division occurs, leading to the extrusion of a 
first polar body. After the extrusion of the first polar body, the 
nucleus enters into a resting stage, a single centrosome remaining 
outside it ; a second division now occurs, leading to the formation 
of a second polar body, which is in turn extruded. The chief 
points of interest in the formation of the polar bodies are (1) the 
similarity of the process of formation, so that neither division can 
'be called a "reducing division"; and (2) the very pronounced 
resting stage which intervenes between them. 

After the extrusion of the polar bodies, the two gametes, 


formed from the products of the division of a single primary cyst, 
fuse again into a single zygote, their pronuclei uniting to form a 
single fertilised nucleus. After this process is completed, a 
membranous or gelatinous layer is formed within the siliceous 
cyst, which Hertwig compares to the yolk-membrane so frequently 
formed by fertilised ova. A multiplication of nuclei now occurs 
within the cyst ; the creature becomes amoeboid, and emerges. 
After emergence, individuals with a single nucleus are not very 
rare, so that the amoeboid young may possibly sometimes divide ; 
but the process has not been observed. 

If the foregoing account be correct, we have in Actinosphaerium 
the only case in the whole animal kingdom in which self-fertilisa- 
tion is shown to be of normal occurrence. There are, however, 
several points to be considered before this view can be adopted 
without qualification. Brauer (2) asserts that the formation of 
Hertwig's " primary " cysts is preceded by a fusion of nuclei, so 
that the nucleus of each primary cyst is really formed from two 
resting nuclei, confirming the view put forward by Anthon Schneider 
in 1877 ; and Hertwig admits that there is a considerable body 
of evidence in favour of this view, though if such a fusion takes 
place it must be a very rapid process, affecting all the nuclei 
in the body simultaneously ; otherwise its occurrence must have 
been frequently witnessed by an observer so skilful and patient 
as Professor Hertwig. The frequent occurrence of plastogamy 
between adult individuals makes it very possible that all the nuclei 
in the same body may not be of the same origin ; and therefore 
the formation of the primary cyst- nuclei by the fusion of two 
others might, in many cases, at least, mean the fusion of nuclei 
originally produced in different individual bodies (Schaudinn). 
Such a preliminary fusion of the nuclei of gametocytes, which 
separate before giving off polar bodies and finally fusing to form 
a zygote nucleus, has been observed in Spirogyra (cf. Klebahn [11], 
quoted by Hertwig) ; and a process of a similar kind a fusion 
of gametocyte nuclei before the extrusion of polar bodies, the polar 
bodies being only given off after division of the fertilised zygote 
appears to occur in some desmids (Closterium, Klebahn [11]). If, 
therefore, we can believe that an individual before encystment has 
normally exchanged some of its nuclei for those of another indi- 
vidual during an antecedent plastogamy, and that a fusion of nuclei 
in pairs takes place before the formation of the "primary" cysts, 
the nuclear history of Actinosphaerium will not be without parallel ; 
but there is direct evidence that normal encystment may occur 
without plastogamy, since Hertwig has succeeded in keeping an 
isolated individual under control through the entire period from 
" hatching " until the production of normal, fertile cysts. Again, 
all observers are agreed that plastogamy is not necessarily followed 


by encystment Avithin any definite period, and Hertwig has obtained 
cysts from individuals in which it had certainly not occurred for 
several weeks. 

ORDER 1. Aphrothoraca, Hertwig. 

Heliozoa usually devoid of a skeletal or gelatinous envelope. A 
membranous envelope, sometimes with siliceous spicules, is only developed 
during encystment. 

Genera Actinophrys, Ehrb. ca. 50 p. Cosmopolitan in fresh water 
and probably cosmopolitan in the sea (Fig. 2). Camptonema, Schaud. 
Numerous small contractile vacuoles and about 50 nuclei. 120-180 p.. 
Marine, Norway. Actinosphaerium, Stein (Fig. 1). Two or more large con- 
tractile vacuoles, numerous nuclei. 1 mm. Cosmopolitan in fresh water. 
Gymnosphaera, Sassaki. Numerous nuclei. Very numerous and very long 
pseudopodia. 140 /x. Pseudopodia up to 800 p. in length. Actinolophus, 
F. E. Schultze. Body usually pear-sheaped. One nucleus. Pseudopodia 
long and thin. Sometimes (always t) with a thin gelatinous membrane 
perforated by the pseudopodia. Attached to a foreign object by a long 
hollow stalk. Body 30 p. in diameter. Stalk 100 p, long by 3-4/4 in 
diameter. Marine. North Sea. The genus Actinosphaeridium, Zacharias, 
freshwater, Germany, is closely related to Actinolophus. The genera 
Zooteirea, Wright, an oval form with a contractile stalk, from the 
Firth of Forth, EstrMa, Frenzel, and Phythelius, Frenzel, are imper- 
fectly known. Phythelius is probably an Alga. Nuclearia (see p. 8), 
Cienkowski, differs from the other Heliozoa in having an amoeboid 
body and pseudopodia without any definite axis. It is sometimes 
regarded as a Proteomyxan. Myxodiscus crystalligerus is a form that is 
doubtfully placed among the Heliozoa. It was found by Prowazek in a 
sea-water aquarium. The genus Archerina, Lankester, which has been 
regarded by some authors as a Proteomyxan and by others as a Heliozoon, 
is now placed by Lankester (1 2) among the Algae. It is the same genus as 
Golenkinia (Chodat.), belonging to the Pleurococcaceae, the naked proto- 
plasm surrounding the green organism in many instances observed and 
figured by Lankester being that of a Vampyrella-like or amoeboid 
organism symbiotic with or merely crawling on the alga. 

ORDER 2. Chlamydophora, Archer. 

Heliozoa with a soft mucilaginous envelope, but without any solid 
skeletal elements. 

Astrodisculus,Greeft (Fig. 2(8)). Body spherical. Pseudopodia very long 
and delicate. Several species recently described by Penard. Freshwater. 
20-40 p. The genus Heliophrys, Greeff, is evidently closely related to 
Astrodisculus, but has also been placed with Heterophrys (see West [21]). 
The form described by Greeff as Chondropus viridis is regarded by Penard 
as a peculiar species of Vampyrella, 



ORDER 3. Chalarothoraca, Hertwig and Lesser. 

Heliozoa with a loose envelope consisting of isolated siliceous or 
chitinous spicules bound together by a mucilaginous or protoplasmic 

Heterophrys, Archer (Figs. 2 (3) and 4). A granular envelope containing 
very delicate and indistinct chitinous spicules. One nucleus and one or more 
contractile vacuoles. 10-20 p.. Freshwater (or marine ?). Sphaerastrum, 
Greeff. According to Penard (14) this genus represents a species of 
Rhaphidiophrys. Elaeorhanis, Greeff. The endoplasm contains a large 
yellow or brown oil -globule. Envelope with attached sand -grains and 
diatoms. 50 /*. Freshwater. Lithocolla, F. E. Schultze. No definite 
oil-globule. Envelope with numerous siliceous bodies, for the most part 
adventitious diatoms, and amorphic grains. Often united together in 
colonies by a gelatinous matrix. 38-45 p-. Freshwater and marine. 
Lithosphaerella, Frenzel. Envelope covered with several layers of sand- 
grains. Freshwater (Argentine) and marine (Mediterranean). All the 
genera so far mentioned were placed by Schaudinn (18) and others in the 
Order Chlamydophora, but were transferred to the Order Ohalarothoraca 
by Penard. 

The following genera have isolated siliceous skeletal spicules and 
are regarded as more typical of the Order. Pompholyxophrys, Archer = 
Hyalolampe, Greeff. Skeleton composed of minute spherical pearls of 
silex. 40-50 JJL. Freshwater. Pinaciophora, Greeff. Skeleton con- 
sisting of overlapping circular plates. 50 p.. Freshwater. The genus 
Pinacocystis, H. and L., which is said to be marine, is closely related to 
Pinaciophora. Rhaphidiophrys, Greeff (Figs. 2 (4) and 9). Skeleton consist- 
ing of a number of minute needles, spindles or half-rings arranged loosely, 
tangentially, and radially in a protoplasmic envelope. This genus con- 
tains several species and is widely distributed in fresh water. It is 
often found in colonial groups. Freshwater and marine (A. pelagica, 
Ostenfeld [13]). Rhaphidocystis, Penard. Spicules of various forms, but 
always different from those of Rhaphidiophrys, scattered in a protoplasmic 
envelope. 12-20 /JL. Freshwater. R. simplex = Acanthocystis simplex, 
Schaudinn. Central Africa. Acanthocystis, Carter (Figs. 2 (5) and 6). 
The envelope of siliceous spicules apparently continuous, formed of 
tangential scales apparently touching one another and an armature of 
radial needles. This genus contains a large number of species, widely 
distributed in fresh water. Two species, A. italica and A. marina 
(Ostenfeld), are marine. The genera Cierikowskia, Schaudinn, and 
Wagnerella, Meresch., from the White Sea, differ from the others in 
the possession of a stalk. 

ORDER 4. Desmothoraca, Hertwig and Lesser. 

Heliozoa provided with a continuous basket-like skeleton perforated 
by holes. 

Clathrulina, Cienkowski (Fig. 2 (2)). Apertures in skeleton relatively 
large. Provided with a stalk. 70 /z. Freshwater. Hedriocystis, H. 



and L. Apertures very small. Provided with a stalk. 20-30 \L. Fresh- 
water. Elaster, Grimm. Apertures very numerous. No stalk. 20 p. 
Freshwater. Choanocystis, Penard. Apertures provided with long funnel- 
shaped collars. No stalk. 13 p.. Freshwater. 

Fio. 0. 

Rhaphidiophrys elcgans. Eight individuals united together by protoplasmic strands and 
surrounded by a skeleton of half- rings. A nucleus is shown in one individual. (After 
Jlertwig and Lesser.) 


A very extensive list of works on Heliozoa will be found in the book by 
Fenard (14). The following is a list of some of the priucipal books and papers 
referred to in the text : 

1. Awerinzew, S. zookhlorellakl u Prostyeishikh (On Zoochlorellae in the 

Protozoa). Protok. St. Peterb. Obshch. xxxi. 1, No. 7 (1900), p. 322. 

2. Brauer, A. Zeitschr. wiss. Zool. Iviii. (1894), p. 189. 

3. Biitschli, 0. Bronn's Thierreich, Protozoa, 1880-82. This contains a biblio- 

graphy up to the year 1879. 

4. Cienkowski, L. Arch, inikr. Anat. iii. (1867). 

5. Crawley, S. P. Ac. Philad. 54 (1902), p. 256. 

6. Grenadier, H. Z. wiss. Zool. v. (1869), p. 259. 

7. Hertwig, R., and Lesser, E. Arch. mikr. Anat. x. (1874), Supp. 

8. Hertwig, R. Abh. k. bayer. Akad. Wiss. xix. (1898). 
9. Test, von Haeckel (1904). 

10. Keeble, F., and Gamble, F. W. Quart. J. Micr. Sci. li. (1907), p. 167. 

11. Klebahn, H. Jahrb. wiss. Bot. xxii. (1890), p. 415. 


12. Lankester, E. R. On Archerina, Golenkinia, and Botryococcus. Quart. J. 

Micr. Sci. lii. (1908), p. 423. 

13. Ostenfeld, C. H. Meddel. Komm. Havundersog. Kobenhavn. 

14. Penard, E. Heliozoaires d'eau douce. Geneve (1904). 

15. Prowazek, S. von. Arb. Inst. Wien, xii. (1900), p. 294. 

16. Schaudinn, F. S. B. Ak. Berlin (1894), (2), p. 1277. (Camptonema.) 

17. Ibid. (1896), v (l), p. 83. 

18. Das Tierreich. Heliozoa (1896). 

19. Verb, der deutscb. zool. Ges. Bonn, vi. (1896), p. 113. 

20. Smith, G. Biometrica, vol. ii. (1902), p. 3. 

21. West, G. S. J. Linn. Soc. xxviii. (1901), p. 308. 
'22. Ibid. xxix. (1903), p. 108. 

THE PROTOZOA (continued) 




Order 1. Physaraceae. 
,, 2. Didymiaceae. 


Order 1. Stemonitaceae. 
2. Amaurochaetaceae. 


Order 1. Heterodermaceae. 

2. Liceaceae. 

3. Tubulinaceae. 

,, 4. Reticulariaceae. 

5. Lycogalaceae. 


Order 1. Trichiaceae. 
2. Arcyriaceae. 
3. Margaritaceae. 


Order. Ceratiomyxaceae. 


Order 1. G-uttulinaceae. 
2. Dictyosteliaceae. 

By J. J. Lister, F.R.S., Fellow of St. John's College, Cambridge. 


THE plasmodial and the spore-bearing phases in the life-history of 
the Mycetozoa have long been known. Many of the generic names 
date from the eighteenth century, and Fries enumerated 192 
species in 1829. 

By the earlier naturalists these organisms were classed, under 
the names Myxogastres or Myxomycetes, with the Gasteromycetous 
Fungi, to which the sporangia of the Endosporeae present in 
miniature a considerable superficial resemblance. Although this 
view of their relationship is now generally abandoned, its influence 
may be traced in the names " capillitium " and " hypothallus " 
which are still applied to structures present in the spore-bearing 
stages of the Mycetozoa. 

It was de Bary (1-3) who first worked out (1859-64) the main 
features of the life-history, showing that the spore hatches out as 
a naked protoplasmic body which assumes a flagellate form, that 
this passes after successive divisions into an amoeboid form, and 
that from the amoebae the large plasmodia arise. 

Cienkowski (7) contributed (in 1863) the important observation 
of the mode of origin of the plasmodia by the fusion of the 
amoeboid swarm-cells. 

De Bary showed how widely different, both morphologically 
and physiologically, these organisms are, not only from the higher 
fungi, but from all those included in the vegetable kingdom, and 
clearly expressed the opinion that they should be regarded as 

In the discussion of the relationships of the Mycetozoa which 
followed the publication of de Bary's work, it was early recognised 
that some of the simple organisms included in the large and ill- 
defined group of the Monadina present phases comparable with those 
of the Mycetozoa. Thus Protomonas amyli and P. parasitica, which 
are parasitic in vegetable tissues containing starch, were found 
by Cienkowski (8) to begin their development as flagellate swarm- 
cells, and then to become amoeboid, in which stage they take in 
or envelop starch grains, which they are able to digest. Later they 
encyst ; the protoplasm withdraws from the undigested food and 
breaks up into a fresh brood of swarm-cells. Moreover, fusion of 
several individuals may occur in the amoeboid stage prior to 
encystment. An encysted resting stage is also found in the life- 

With the object of introducing order into the heterogeneous 
assemblage of organisms which were, at the time of writing, classed 
as Monadina, Cienkowski proposed (5) to restrict this name to forms 
which passed through a life - history approximating to that of 

The group, as thus limited, was regarded by him (8) as inter- 
mediate between animals and plants, and presenting affinities in 


several directions ; among others with unicellular algae, the 
Mycetozoa and such forms as Actinophrys. Of these alliances, that 
with the algae is the least satisfactorily established by Cienkowski, 
but that between the " Monadina " and the Mycetozoa has been 
generally accepted by de Bary and later writers. 

Zopf (24) considerably enlarged the "Monadina " of Cienkowski, 
and in 1887 included them in the Mycetozoa, distinguishing the 
forms here included, as the Eu-mycetozoa. This course is open to 
objection on several grounds. The "Monadina" of Zopf appear 
to be still a very heterogeneous collection of forms, and their 
inclusion in the Mycetozoa tends to obscure the well-marked features 
of this group. Further, though the affinity of some of the 
Monadina with the Mycetozoa seems probable, others are as closely 
connected with the Heliozoa, in which class the majority of them 
are, in fact, included by Biitschli (4). 1 

Hence the limits of the Mycetozoa, as here understood, are the 
same as those drawn by de Bary. They include (1) the Sorophora 
of Zopf (the Acrasiae of Van Tieghem) ; (2) the remainder, and 
great majority of the species, for which de Bary retained the old 
name of Myxomycetes. The only objection to retaining this name 
is that it is generally used as synonymous with Mycetozoa. The 
term Eu-mycetozoa would have been preferable, but it is used by 
Zopf to include the Sorophora. Delage and Herouard have applied 
the name Euplasmodida to the higher group, a course which avoids 
all confusion, and emphasises one of the chief characters which dis- 
tinguishes it from the Sorophora. 

In a more recent work (25) Zopf has included the Labyrinth uleae as 
a sub-order of the Sorophora. He has shown that the singular network 
described by Cienkowski in Labyrinthula, by which the individuals are 
united, is pseudopodial in nature, and regards the whole colony as forming 
a body of the nature of a plasmodiuni, to which he applies the name 
thread-plasmodium. There appears to be no evidence, however, that the 
term plasmodiuni is any more applicable to the colony of Labyrinthula 
than it is to those, e.y., of Mikrogromia, or the colonial Radiolaria. The 
actively parasitic habit, the entirely aquatic life, the defined shape of the 
members of the colony, and the absence of any proof that it is formed 
by fusion of individuals, keep Labyrinthula distinct from forms hitherto 
included in the Sorophora. Penard (20a) has recently extended our know- 
ledge of Chlamydomyxa, showing that the " oat-shaped corpuscles " are 
not nucleated, and therefore not comparable with the fusiform bodies of 
Labyrinthula ; and also that the contents of the cysts escape as flagellate 
zoospores. Penard finds a great analogy between this genus and the 

1 Whatever position is ultimately assigned to the " Monadina " of Cienkowski 
and Zopf, it is desirable that this name for them should fall into disuse, for it is now 
applied in zoological works to the simpler members of the Flagellata, in which the 
flagellate and not the amoeboid stage is predominant in the life-history. 


Euplasmodida, a view which is by no means shared by the writer of this 
article. The presence of chlorophyll bodies and the stiff little-branched 
character of the pseudopodia are altogether foreign to the present group, 
and here again the plasmodial nature of Ghlamydomyxa is far from being 
established. Both these genera are in the present treatise dealt with 
separately (pp. 274, 280). 

In addition to the remarkable phenomena presented by the 
plasmodium of the Euplasmodida, the characteristic and unique 
feature of the Mycetozoa, as a group, is that belonging, as 
the earlier stages of their life-history show them to do, to the 
animal stock, and developing their sporophores and sporangia in 
air, these structures have been differentiated into a series of 
forms analogous with the sporophores met Avith among different 
orders of fungi. So close is the resemblance in many cases, that 
sporangial forms of each of the three main divisions have been 
classified among the several orders of fungi : Dictyostelium 
(Sorophora) among the Mucorinae ; Cemtiimyxa (Exosporeae) with 
the Basidiomycetes Polyporus and Hydnum ; and various members 
of the Endosporeae with the Gasteromycetes. 


(a) The Swarm-Cell or Zoospore. 

The spores of the Mycetozoa are produced not in water, as are 
those of the Monadina (except Bursulla), but in air, and they are 
able to retain their vitality in the dry state for as many as four 
years, undergoing no apparent change except a collapse of the 

spore owing to the shrinking of the 
contents on drying. When carried 
into water, they rapidly swell and 
cv resume their original form, which is, 
in nearly all species, spherical. As 
they lie in water one or more contrac- 
tile vacuoles make their appearance in 
the protoplasmic contents, and after 
a period varying from a few hours 
FIO. i. to a day or two, the spore wall is rup- 

The hatching of a spore of Fuligo septica. turecl, and the Contents slip OUt and 
x 1100. a, spore; 6 and c, contents .. . . . . , 

emerging and undergoing amoeboid move- 116 tree in the Water a maSS OI Clear 

^ore\tege^ff;\!v, 'Contractile vacuoie. 00 " protoplasm, containing the nucleus 

and contractile vacuoles (Fig. 1). 

The first movements in the free state are amoeboid, but an 
elongated shape is soon assumed ; and a flagellum, protruded ten- 
tatively at first, becomes established at one end. The organism 


which thus enters the swarm -cell or zoospore stage swims free 
in the water with a peculiar dancing movement produced by the 
lashing of the flagellum. In this movement it rotates about its own 
axis, and also moves as though over the surface of a cone, the apex of 
which is situated at the posterior end of the zoospore (de Bary). 
It is of an elongated pyriform shape, the narrow (" anterior ") end 
being continued into the flagellum, which is about half to two- 
thirds the length of the body. The thicker (" posterior ") end may 
be evenly rounded, and is then curled somewhat to the side, but 
is often extended in short pointed pseudopodia (Fig. 2, ). The 
protoplasm of the anterior part is hyaline, and a layer of hyaline 
protoplasm invests the rest of the body, the interior of which is 
granular. The nucleus, with its contained nucleolus, lies in front, 
At the base of the flagellum, and the contractile vacuole at the 
posterior end. Non-contractile vacuoles (some of which at least 
may be food- vacuoles) are also present in the granular protoplasm. 
The particles of the latter exhibit a change of position within the 
body, which in the large swarm-cells of Amaurocliaete atra recalls the 
streaming movement characteristic of the plasmodia of the later stage. 

Instead of swimming free, the swarm -cells may temporarily 
assume an attached creeping mode of progression, in which the 
body is elongated, and the flagellum, ex- 
tended in front, turns from side to side 
with movements which appear to be ex- 
ploratory in purpose. Sometimes the body 
is contracted and sends out pseudopodia 
from all parts of the periphery (Fig. 4, c). 

Bacteria abound in the wet places among 
decaying vegetable matter, in which the 
spores hatch. These are captured by the 
zoospores by means of the pseudopodia ex- 
tended from their posterior ends and drawn 
into the body, where they are digested in 
vacuoles (Fig. 2) (15). De Bary, to whom 
this mode of obtaining food by the zoospores 
was unknown, states (8, p. 452) that their 
nourishment is exclusively saprophytic at 
this stage. 
it may be 
appears very probable that it is both holozoic and saprophytic. 

The swarm -cells multiply by division. In this process the 
flagellum is withdrawn, the contractile vacuole disappears, and the 
body assumes a rounded form. The nucleus, passing to the centre, 
divides by karyokinesis (Fig. 3), and as the daughter nuclei resulting 
from this division separate the protoplasm becomes constricted, and 
-division occurs in a plane transverse to the axis of division of the 

Zoospore of Stcmnnitis fusca, 
showing successive stages in 
the ingestion of a bacillus, 
x 800. In , it is captured by 
one of the pseudopodia at the 
hind end ; in c, it is enclosed 
in a digestive vacnole. Another 
bacillus is contained in an 
(After A. 

It is impossible to deny that Anterior vacuole. 

. . J . Lister, 15.) 

in part saprophytic, and it 


nucleus. A contractile vacuole has, meanwhile, appeared in each 
daughter-cell, at a point remote from the plane of division, and 
each develops a flagellum after separation is complete (15). It is- 
probable that many generations of swarm-cells produced in this 
manner succeed one another during this stage of the life-history. 

When the zoospores are 
treated by Heidenhain's hae- 
matoxylin method, or with 
picrocarmine, a reticulum comes 
into view in the nucleus, and 
the nucleolus takes a dark stain. 

FIG. 3. 

Three stages in the division of 
zoospore of Keticvlaria lycoperdon. 
x 1000. (After A. Lister, 17.) 

FIG. 4. 

Zoospores of Badhamia panicea, 
stained, x 650. 

The nucleus is sometimes round (Fig. 4, b), but more often it is 
pyriform, being drawn out towards the base of the flagellum 
(Fig. 4, a). The protoplasm intervening between the nucleus and 
the flagellum is differentiated from the rest, and takes a darker 
stain. It thus forms a more or less bell-shaped investment of the 
former, the contour of which is most clearly seen in specimens- 
which have assumed an amoeboid shape without retracting the 
flagellum (Fig. 4, c). 

Plenge (21) first called attention to this bell-shaped structure; and 
Jahn (11), who has recently investigated it afresh, considers that it is- 
part of the spindle formed in nuclear division when the zoospore divided^ 
and remaining in connection with the daughter nucleus. Jahn's figures 
illustrating this point are very clear, but he does not explain how the 
structure is formed in the zoospore prior to its first division. 

In this and also in the succeeding stage a resting phase may 
intervene between periods of activity. In it the flagellum and 
pseudopodia are withdrawn, and the protoplasmic body rounding 
itself into a sphere secretes a hyaline cyst-wall. These cysts are 
known as microcysts. The formation of microcysts may be readily 
induced by allowing a cultivation of swarm-cells to dry up, but 
dryness is not a necessary condition for their production, for they 
are formed in water, and some are present in almost every cultivation 
of swarm-cells. 

(b) The Amoebula. 

After remaining for a period of uncertain duration in the stage 
of their life-history in which the dominant form is that of the free' 



swimming flagellate zoospore, the flagellum is permanently with- 
drawn and the organism passes into the amoeboid stage, which, as we 
have seen, may be temporarily assumed daring the flagellate period. 
They now creep about, adherent to other objects, emitting blunt 
pseudopodia, and in this as in the preceding stage they may pass 
into the condition of microcysts. 

Each individual in the amoeboid phase of the life-history is the 
lineal descendant, through the successive divisions of the flagellulate 
phase, of a particular spore ; but from 
the amoeboid phase onward the in- 
dividuality is lost. This results from 
the remarkable process, first seen by 
Cienkowsld (7), of fusion of the 
amoebulae to form plasmodia. The 
amoebulae present in a particular area 
draw together into groups, becoming 
endowed, apparently, with the power 
of mutual attraction, and the groups, 
once formed, act as centres to which 
neighbouring amoebulae, scattered 
through the water, converge. After 
coming in contact with one another 
they remain at first visibly distinct, 
but after a short time a complete 

fusion of the protoplasm occurs. In this manner, the amoebulae 
from all sides falling in and fusing in the common mass, the 
plasmodia are produced. 

(c) The Plasmodium. 

The name plasmodium was first applied by Cienkowski in 1862 
(6, p. 326) to the large expansions of protoplasm which form the 
dominant phase of the life-history of the Euplasmodida. On his 
subsequent discovery (7), in 1863, of their mode of origin by the 
fusion of amoeboid swarm-cells, Cienkowski stated (p. 421) that such 
a mode of origin must be included in the definition of a plasmodium. 

The question arises whether, in this fusion of amoebulae to form 
the plasmodia, we have a phenomenon comparable with the conjuga- 
tion of the gametes of other forms, a view to which the mutual 
attractiveness with which the amoebulae become endowed appears 
to offer some support. If the analogy were complete, we should 
expect that a fusion of nuclei would occur as well as a fusion of the 
protoplasm of the amoebulae. But the evidence which we have at 
present as to the behaviour of the nuclei lends no support to this 
view. As many as eight amoebulae have been watched successively 
fusing into a common mass, and their eight nuclei have been seen, 
distinct, in the young plasmodium thus formed (18, p. 5). When 

Fio. 5. 

Amoebulae of Dulymium di/ormc 
uniting to form a plasmodium. a, 
separate amoebulae ; m, microcysts ; 
pi, young plasmodium with ingested 
bodies, x about 320. (After A. Lister, 



the number of fused amoebulae increases, direct observation of the 
behaviour of the nuclei is, owing to their small size and the bulk 
and movements of the protoplasm, increasingly difficult, and soon 
becomes impossible. 

Before describing the plasmodia in detail, it may be briefly 
stated that they are masses of naked protoplasm of indefinite size, 
containing numerous small nuclei. As de Bary discovered, they 
are capable, under certain conditions, of passing into a passive 
condition known as the Sclerotium, in which the protoplasm is 
aggregated in cysts (Fig. 8), which together form a mass of horn- 
like consistency. On the return of favourable conditions the 
plasmodium resumes the active condition. 

The mode of life of the plasmodium differs in different species, 

FIG. 6. 
Part of a plasmodium of Bailhamia ittriculans expanded over a slide, x S. 

some (as in most of the Trichiaceae and Arcyriaceae) penetrating 
the interstices of dead wood, others (as of most species of Craterium 
and Didymium) living among heaps of decaying leaves, while one 
species, Badlmmia utricularis, feeds on the surface of living fungi 
which grow from the bark of dead trees. 

The plasmodium expands over surrounding objects and moves 
about, taking in nourishment. When exposed, it is seen by the 
naked eye to be traversed by systems of vessel-like thickenings, the 
main trunks of which divide and subdivide as they approach the 
periphery, and are in free communication by the anastomosis of 
their branches (Fig. 6). 

The border of the plasmodium in the direction towards which 
it is moving generally consists of a continuous film of protoplasm, 
traversed by smaller branches of the system, but in the other parts 
the film is generally not continuous, being interrupted in the inter- 


spaces between the thickenings. Hence in these regions the plas- 
modium consists of a reticulum of anastomosing branches, extended 
over the substratum. The arrangement of the branches closely 
resembles that of the vessels traversing the mesentery of a mammal, 
and, before their relation to the spore-bearing stage of the life- 
history was known, the name Mesenterica was, in fact, given to 
plasmodia of certain forms, under the supposition that they repre- 
sented a new genus of fungi. 

The form and degree of concentration of the plasmodium 
vary widely according to circumstances. Sometimes it is 
aggregated in a thick layer on the surface, as after emerging from 
the interstices of a mass of rotten wood or tan, at other times it 
is widely expanded in a thin layer of exquisite delicacy. Fries 
relates hoAv the plasmodium of Diachaea elegans which he had 
laid in his hat, while collecting, spread within an hour over a 
great part of the latter in an elegant white network. 

By suitable manipulation the plasmodia may readily be induced 
to spread over glass cover-slips, and may thus be examined micro- 
scopically. 1 When thus seen the vessel-like thickenings are found 
to be, in fact, streams of moving protoplasm. The flow may be 
traced from the larger branches through the smaller into the 
advancing border of the plasmodium, which becomes swollen and 
more opaque as the streams pass into it. After a short time the 
current is seen to slacken, then to stop, and shortly to begin again 
in the reverse direction, the margin becoming thinner and more 
transparent as the protoplasm leaves it. In a short time the flow 
is again reversed, and again directed to the advancing border. 
Thus a rhythmic flow, towards the margin and away from it, is 
kept up through the plasmodium the period in each case being, 
in healthy conditions, about a minute and a half to two minutes, 
though its duration is always longer in the direction in which the 
plasmodium is moving than in the other. 

The plasmodium is invested by a thin layer of homogeneous 
hyaline and colourless protoplasm. Within this the protoplasm is 
highly granular. 

The hyaline layer is exceedingly thin over the greater part of 
the periphery, but at the advancing border it is of considerable 
breadth. The advance over the substratum occurs chiefly while 
the flow in the veins is directed towards this border. Under 
these circumstances the border becomes more and more turgid, and 

1 An easy way of making microscopic preparations of living plasmodia is to lay 
out a number of cover-slips on a plate, sprinkle them with rain-water, and then to 
s., Uter small fragments of sclerotium over them. In a moist atmosphere the 
encysted protoplasm resumes the active stage in the course of a few hours, and the 
small plasmodia thus arising spread in delicate fan-like expansions over the glass. 
The cover-slips may then be mounted over a hole in wet blotting-paper, on a slide, or 
in some other manner, ensuring the maintenance of a moist atmosphere. 


small rounded lobes of hyaline substance are seen to start forward, 
and then to become stationary, as though the surface tension had 
momentarily been overcome by the pressure from within, and had 
then been rapidly renewed. It is to be observed that the contents 
of such a newly-formed lobe are at first not, as might have been 
expected, the granular protoplasm which flows in the " veins," but 
they are hyaline, the passage of the granules into the interior of 
the lobe occurring subsequently. 

The material in the " veins " appears to be of highly fluid 
consistency, the granules moving over one another with great 

*,^x>:^-^:^^-:^:! : -''^ ' ''' . ''''", '. .-:V>dr-:-- : - f ^ 

FIG. 7. 

o, part of a stained plasmpdium of 5. utricularis. n, nuclei, x 110 ; b, nuclei, x 500. Some 
.are in process of simple division, c, part of a plasmodium in which the nuclei are in simul- 
taneous division by karyokinesis. <?-/, other stages in this mode of division, x 650. 

freedom. When a small channel is watched it frequently occurs 
that an ingested sclerotium cyst or other large object blocks a 
narrow part, and the flow in the channel is temporarily checked. 
If the object ultimately passes on, its passage is followed by a 
gush of the protoplasm behind it, at increased velocity, the flow 
gradually resuming its normal rate. When a vein traversing a 
continuous portion of the plasmodial film is examined the flow is 
seen to be rapid at the centre and slower at the sides. 

The phenomena presented by the circulation in the veins suggest 
the view that their contents are passively propelled, as the result of 
the contraction of the more external part of the plasmodial substance. 


De Baiy concluded (2, pp. 43-51) that besides such a positive 
vis a tergo, due to contraction of the protoplasm in the regions from 
which the flow occurs, there is evidence of a negative pressure 
exercised by the plasmodium in the regions towards which the flow 
is going, and due to its expansion from the previous state of 

While the conclusion appears probable that the streaming 
movement is due, in part at any rate, to the contraction of the 
outer portions of the protoplasm, we may bear in mind that such 
an explanation appears inapplicable to other phenomena, which we 
should expect to belong to the same category, such as those 
exhibited by the pseudopodia of the Foraminifera, in which 
streams of granules course along a filament of extreme tenuity in 
opposite directions. 

When a piece of sclerotium resumes activity on being wetted, 
it sends out a fan- like expansion over the substratum, and the 
rhythmic flow is seen to be alternately away from the central mass 
and back to it ; but as the fans extend farther over the substratum, 
the flow in the several parts of the plasmodium becomes less and 
less co-ordinated, in proportion as they separate from one another. 
The several parts separate into distinct plasmodia, and distinct 
plasmodia fuse with complete freedom. 

Reaction of Plasmodia to External Conditions. Experiments testing 
the reaction of plasmodia to variations in external conditions have 
led to some positive results, an interesting account of which is 
given by Stahl (22). 

During the vegetative period of their existence plasmodia move 
from the drier to the moister parts of their substratum, though at 
the approach of the spore-producing stage the movement is in the 
opposite direction, the organism seeking the driest part of its en- 
vironment whereon to undergo its change into spores. Connected 
apparently with the favourable influence of a moist atmosphere is 
the phenomenon, familiar to tanners, of the " flowering of the tan- 
heaps " at the approach of wet weather. This consists of the 
emergence at the surface of the bright yello.w plasmodia of Fuligo 
septica, commonly known as Flowers of Tan, which abound in the 
heaps, and, except under such conditions (and at the approach of 
sporulation), inhabit the deeper parts of the heap. 

When water is allowed to flow through the substratum, 
plasmodia move in a direction opposite to the current, a tendency 
which may be utilised for the purpose of isolating them for 
experimental purposes. By arranging strips of filter paper, through 
which water is flowing, so that their lower ends rest on the mass 
containing the plasmodia, the latter will crawl up the filter paper, 
and may thence be transferred, in the same manner, to glass slides. 


The presence of substances suitable for food exercises a strong 
attraction on plasmodia. When the spreading border touches 
such a substance the streaming movement is at once quickened in 
this direction, and the outlying lobes being drawn in, the whole 
plasmodium is rapidly concentrated on the nutrient material (14). 

The contrary effect is seen when harmful substances are brought 
into their neighbourhood. 

The plasmodia of many species are said to shun the light, but 
this is not the case with all ; that of Badhamia utricularis, for 
example, will, if a moist atmosphere be maintained, continue to 
spread over the pilei of the fungi on which it feeds, though these 
may be exposed to full sunlight. 

Nuclei. The plasmodia are multinucleate from their origin; 
but from the fact that a minute plasmodium a few millimetres in 
diameter will grow, when supplied with food, till it is many inches 
in diameter, and that the nuclei are then as numerous, in a small 
sample, as they were before the growth had occurred, it is clear 
that the nuclei increase in number pari passu with the growth of 
the protoplasm. There is reason to believe that this increase occurs 
in two ways, (a) A simultaneous division of the nuclei by karyo- 
kinesis has been found to be in progress when plasmodia (of Badhamia 
utricularis, Fig. 7, c-f) are stained (17, p. 541) a process comparable 
apparently with the simultaneous division of nuclei which occurs in 
the vegetative stage of Actinosphaerium. (b) Multiplication by simple 
division is not easy to establish, where, as in this case, prolonged 
observation of the nuclei in the living state is rendered difficult by 
the movement of the plasmodia, but the following observation appears 
to show that it is of frequent occurrence in their groAvth : 

A plasmodium of Badhamia utricularis, spreading and feeding on 
the pilei of the fungus Auriculuria, increased in size about fourfold 
in fourteen hours; and during this time a small portion of it was 
removed, smeared on a cover-slip, and fixed every quarter of an hour. 
On staining the 56 samples so obtained, the nuclei were found to be 
approximately equally abundant in all, and presented considerable 
differences in size, but in no case was there any indication of karyo- 
kinetic division. Now in the karyokinetic division of nuclei which 
occurs prior to spore-formation (see p. 52) the process lasts from one 
to one and a half hours. Assuming the same duration for the 
karyokinetic division of the nuclei in the growing plasmodium, and 
bearing in mind that the division in this manner, when observed, 
was simultaneous, we must conclude that it had not occurred in 
the fourteen hours during which the observations were made ; yet 
from these observations it appears that in this period the number 
of the nuclei had increased about fourfold (18, p. 9). As a fact, 
the appearance of the nuclei in various phases of constriction is of 
common occurrence when stained plasmodia are examined with a 


high power (Fig. 7, b), but the appearance is so similar to that of 
overlapping nuclei, that without the confirmation afforded by the 
experiment above described, the conclusion, that in addition to a 
periodic (?) increase by mitosis, the nuclei multiply by simple 
division, could hardly have been accepted as secure. 

With regard to the distribution of the nuclei, it is to be observed 
in stained preparations, in which the plasmodium has been suddenly 
killed, that they appear to be as numerous in proportion to the bulk 
of the protoplasm in the veins as they are in the film of the plas- 
modium on either side of them. 

In size the nuclei vary from 2 '5 to 5 /x. In the resting condi- 
tion they present a well-marked reticulation and a distinct nucleolus. 

In mitosis a well-marked spindle is formed, and the chromosomes 
are rounded and compact. In number the latter appear to be 
about 8 or 9, in Trichia (see, however, p. 65). It may be noted 
that as in other Protozoa the nuclear membrane is maintained 
until after the separation of the chromosomes to form the daughter 

Contractile Vacuoles abound in the peripheral layer of the plas- 
modium, and may be readily seen in the expansions between the 
channels. They are generally about 7-8 p in diameter. 

The protoplasm contains abundant granules, of minute size, 
the nature of which has not been ascertained. In one group of 
Mycetozoa, the Calcarineae, granules of carbonate of lime abound 
in the plasmodia. They are not present in other species, and their 
relation to physiological processes is obscure. 

The plasmodia of many species are white, but those of others 
are yellow, pink, purple, or green, and owe their colour to a fluid 
pigment scattered in small drops through the protoplasm. In the 
Calcarineae, the fluid pigment invests the granules of lime. 

The Food of Plasmodia. The plastnodia of the great majority of 
the Mycetozoa feed on the decaying vegetable matter among which 
they live. Their mode of nutrition must be regarded as both 
saprophytic and holozoic, for they are able to absorb nutrient 
matters in solution (cf. Stahl, 22) as well as to engulf their food. 
Those living among leaves and under bark are found charged with 
particles which have been ingested, and the undigested portions 
are found strewn along the track they have traversed. Badhamia 
utricularis is exceptional in feeding on living fungi (Stereum, Auri- 
cularia, etc.), though it will also live and thrive on the same fungi 
after they have become dried, if they are wetted again with water. 

Experiments have shown that proteids (coagulated albumen, 
sclerotium cysts), taken in by plasmodia, are digested in vacuoles 
into which an acid is secreted by the surrounding protoplasm (see 
the experiments by Miss Greenwood and Miss Saunders, 10), 


although the reaction of the plasmodium as a whole is alkaline 
(Metschnikoff, 19). Pepsine, the presence of which in plasmodia of 
Fuligo was shown by Krukenberg (12), is doubtless the agent by 
which, acting in this acid medium, the digestion is brought about. 

Raw starch grains which had been ingested were found to pass 
unaltered through the plasmodium of Badhamia utricularis, though 
grains which had been previously swollen in warm water were 
digested (14). 

The plasmodium of this species at any rate has the power of 
dissolving cellulose. This is evident from the nature of its food, 
and has also been directly observed (14) when a plasmodium was 
seen to extend over the hyphae of a mould. The cellular walls of 
the hyphae were dissolved " like sugar in hot water " as soon as the 
hyaline border of the plasmodium reached them. 

The Sclerotium Condition. As in the earlier phases of the life- 
history, a passive condition may, as we have seen, be assumed in 
the plasmodium stage, the protoplasmic mass breaking up into 
cysts and assuming as a whole a firm consistence. To this con- 
dition de Bary gave the name Sclerotium. As it supervenes, 
the streaming movements gradually cease, foreign bodies are 
extruded, and the plasmodium becomes separated into distinct 

masses, each of which contains 10-20 
nuclei, and secretes a membranous cyst- 

The assumption of the sclerotium 
condition is readily induced by allowing 
plasmodia to dry, and when so treated 
they assume a firmer and firmer con- 
sistency, until the masses of cysts attain 
a hard and horn-like condition, in which 

Part of a section of the plas- . 

medium of Sadkamia utricularis vitality may be preserved for as many 

when passing into the sclerotium ,-, c, , , 

condition, x 310. , a nucleus, as three years. Sclerotium cysts may, 

however, be formed in water, but the 

conditions under which this occurs are obscure. When the dry 
sclerotia are placed in water the protoplasmic masses absorb or 
break through the cyst-walls, fuse together, and the active plas- 
modial condition is resumed. The revival occurs in a few hours. 

It is to be noted that the unit represented by the sclerotial 
cyst is different from the microcyst of the preceding stages, which 
was uninucleate, and also from the sporangium of the succeeding 
stage, which is much larger, and contains a much greater number of 

(d) The Formation of Sporangia. 

The conditions under which plasmodia pass into the succeed- 
ing phase, that of spore-production, are in part obscure, but one 


element in this result is the absence of further nourishment. In a 
cultivation of Badhamiu utricularis, after the plasmodium has been 
supplied with abundant food, arid has increased largely in bulk, the 
formation of sporangia may generally be induced by withholding 
the supply of fungus, which is the food material of this species. 
If while food is withheld a suitable substratum, such as clean 
sticks, is supplied, the plasmodium will generally creep on the 
sticks and there form into sporangia. 

The mode of formation of the sporangia in this species may 
be described as characteristic of the majority of Mycetozoa, the 
principal departures from the type being subsequently noticed. 

As seen by the naked eye, the plasmodium previously extended 
in a diffused network over the substratum is seen to become 
aggregated in lobed masses 0*5 to 1 mm. in diameter, which in this 
species are grouped closely together, and vary in number from a 
few to many thousands, in proportion to the size of the plasmodium. 
These are at first connected by the veins of the plasmodium, and 
may be seen to expand and contract in accordance with the 
direction of the streaming movement, which is still maintained. 
Gradually, however, the veins connecting them diminish, and soon 
the whole protoplasm is completely segregated into distinct lobes, 
or young sporangia. 

While the formation of the sporangia is in progress, all re- 
maining foreign bodies which have been 
ingested with food in the plasmodial 
stage are expelled, and a secretion takes 
place of a structureless, transparent sub- 
stance which serves for the support 
and enclosure of the spores. At the 
surface of each of the lobed masses, 
constituting the young sporangia, is 
thus formed a sporangium wall, which 
in the mature state is a thin wrinkled 
membrane, completely investing it. At 
the constricted base of the sporangium 
this is continued to the substratum as a 
slender stalk of varying length (Fig. 9). 

While the sporangium wall is 
secreted on the surface of the spor- 
angium, a similar process occurs along 

certain tracts throughout the interior, a , a group of sporangia of Badhamia 

aivino- risp /in tnia cnpr>if>cA fn an -mocrn utricularis. X 12. b, a cluster of 
giving rise (in tniS Species; to an anaSCO- spore s ; c> a single spore ;d, part of the 

mosing network of flat bands with capillitium containing lime granules. 
, . . b and d x 170. (After A. Lister, 18.) 

broad, thin expansions at the points ot 

junction (d). From a superficial resemblance to a structure in 

Gasteromycetous Fungi, this network traversing the interior of 


the sporangium is known as the capillitium. At the periphery it is 
continuous with the sporangium wall. 

The lime granules, which existed free in the plasmodium, pass 
out of the protoplasm simultaneously with this secretion. Some 
are sparsely scattered through the sporangium wall, but the 
majority are closely packed in the strands of the capillitium, which 
are white and brittle in consequence (Figs. 9, d, and 10). 

Until the secretion of sporangium wall and capillitium is 
complete the protoplasm remains a homogeneous mass, with 
multitudes of nuclei scattered through it. Their completion is 
followed by a division of the nuclei by karyokinesis, which occurs 

Fio. 10. 

20. To the left are three sporangia, the walls of which 
H naniiijtium. Three to the right are unopened ; above 
of the capillitium. 

simultaneously throughout the sporangium and occupies from one 
to one and a half hours (Fig. II). 1 While this is in progress the 
protoplasm breaks up into rounded masses which contain some 6-10 
nuclei, but they subsequently divide into masses, each containing 
one of the dividing nuclei ; and as the nuclear division is completed 
and the daughter nuclei draw apart, a further division of the 
protoplasm occurs, and each nucleus then occupies a single mass 
of protoplasm (Fig. 12). These masses are the young spores. 
They soon secrete a spore-wall which is of a violet-brown colour^ 

1 This was first observed by Strasburger (23) in Trichia fallax. The observation 
has been repeated by my father in two other species of Trichia, and in representatives 
of the genera C'omatricha, Physarum, and Badhamia (17), and, since that paper was- 
published, in Reticularia and Arcyria. 



and covered with minute spines or tubercles. The spores are ap- 
proximately spherical, and 9 to 12 yu. in diameter. In several species 

the spore -wall has been found to 
give the reaction of cellulose. 

Fio. 11. 

Tart of a section through a young 
sporangium of Trichia varia, showing 
the division of the nuclei prior to 
spore - formation. x 650. c, capil- 
litium thread ; n, a nucleus. In 
several cases the axis of the dividing 
nucleus is directed towards us, and 
the karyokinetic figure is therefore 
not displayed. 

Part of a section through a spor- 
angium of Trichia raria after the 
spores are formed. Capillitium 
threads are seen in longitudinal and 
transverse section, x 650. 

The ripe sporangium thus consists of a mass of spores, 
enveloped by the sporangium wall and traversed by a supporting 
reticulate capillitium, which, like the wall, has a dry membranous 
character, though charged throughout with white granules of lime. 
As ripening proceeds the sporangium wall becomes more and more 
friable, until it breaks and the spores are spread abroad on the 
lightest currents of air. 

Considerable variations of structure are presented by the 
sporangia of the Mycetozoa. The stalk may be absent altogether, 
the sporangia being sessile on the substratum (Fig. 13, e). When 
present it is usually solid, but may be hollow, and sometimes, as in 
Trichia fallax, may contain cellular elements, which appear to be 
aborted spores. 

In many species the stalk is continued in the interior of the 
sporangium as a structure known as the columella, which may reach 
to the apex or terminate short of it. A columella may, however, 
be present in sessile sporangia, as in species of Chondrioderma 
(Fig. 13, e}. 

Stalked sporangia are, at their first formation, sessile, and in 
the majority of cases the stalk may be regarded as the basal part 
of the sporangium wall, which has shrunk and fallen in about the 
base of the sporangium, as the latter has risen above the substratum 
(Figs. 13, a, and 15, a) ; but in the Stemonitaceae the stalk, with its 



continuation, the columella, is, as de Bary showed, an axial structure 
secreted in the interior of the young sporangium (Fig. 14, a-e). In 
the formation of these sporangia the basal portion of the stalk is 
formed first and additions are made to the apex as the protoplasm 
climbs Up this axial support. In Stemonitis fusca and splendens the 
stalked sporangia may attain a height of 20 mm. 

In addition to the skeletal or supporting structures of the spore- 
bearing stage above mentioned, another is present in many genera 
the hypothallus. This consists of a network of strands or a con- 
tinuous film, formed of the same material as the other supporting 
structures, extended over the substratum, and forming the base 
on which the sporangia are inserted (cf. Fig. 13, d). Its presence 
apparently depends on the occurrence of the secretion, in the later 

FIG. 13. 

a, sporangia of Physarum nutans, Pers., x 15. 6, piece of sporangium wall, with groups of 
lime granules, capillitium threads, with lime-knots (k) and spores of Physancm, nutans, x 210. 
c, spore of same, x 450. d, sporangia of Craterium pedunculatum, Trent, each with a discoidal 
hypothallus at the base of the stalk, x 17. e, sporangia of Chondriodermu tcstaceum, Host., 
showing the double sporangium wall (outer layer with lime, inner membranous), and in the 
upper sporangium the columella, x 15. /, threads of the capillitium of the same, x 280. g, 
group of crystals of lime from the wall of Spumaria alba, x 210. h, a crystalline disc from 
the sporangium wall of Lepidoderma tigrinuam, Rest., x 210. (After A. Lister, 18.) 

stages of the plasmodial condition, of the substance which dries into 
the supporting material its reticular or continuous character corre- 
sponding with the state of diffusion of the plasmodium during its 

The sporangium wall may consist of two layers as in Chondrioderma 
(Fig. 13, e), where the outer is densely charged with lime granules, 
and the inner is membranous and free from lime. In some species 
of Craterium (Fig. 13, d) the upper portion of the sporangium wall 
forms a lid, which readily falls away, exposing the contents. In 
Didydium (Fig. 14,/) and Cribraria the wall of the mature sporangium 
is represented wholly or in part by an open network, through the 



meshes of which the ripe spores escape ; and in Comatricha it is 
evanescent, and disappears soon after the sporangia are ripe. 

The capillitium also presents great variation. In the genera form- 
ing the Calcarineae the lime may be uniformly distributed through 
it (Badhamia, Figs. 9 and 10) or collected into lumps ("lime-knots") 
at the points of junction of the reticulum (Physarum, Fig. 13, b, 
Fuligo, Craterium). In Chondrioderma (Fig. 13, e and /), Didymium, 
and others the lime is only laid down in or on the sporangium wall 
and the capillitium is free from it. The strands of the capillitium 
are generally, though not invariably, continuous at the periphery 
with the sporangium wall, and internally with the columella, if this 
structure is present. 

FIG. 14. 

a, four sporangia of Stcmonitis splendens, Rost.; that to the right is represented free from 
spores and shows the columella extending nearly to the top ; x 2. b, part of an empty 
sporangium of S. splendens, showing the columella (c) and a branch springing from it and 
dividing to form the surface network of the capillitium. To the right a group of spores, d, e, 
stages in the development of the sporangia of Stemonitis ferruginea, Ehrenb., showing the 
development of the columella in the axis of the young sporangium. The space between the 
columella and the protoplasm is artificial. /, empty sporangium of Dictydium umbilicatum, 
Schrad., x 30. (d and e after de Bary, 2 ; the other figures after A. Lister, 18.) 

The capillitium attains its most elaborate development in the 
Arcyriaceae and Trichiaceae (Fig. 15). In the former it consists of 
an elastic network, attached or not to the base of the sporangium, 
but free from its sides, and with the strands beset with spines or 
transverse thickenings, resembling cogs on a wheel (Fig. 15, /). At 
maturity the evanescent film of the sporangium wall gives way and 
the capillitium expands into a long loose tangle, scattering the spores. 

In the Trichiaceae the threads of the capillitium have spiral 
thickenings. In Hemitrickia the threads are united into a network, 
as in Arcyria, but in Trichia they are usually unbranched and lie 
free among the spores (Figs. 11, 12, and 15, b). Owing to their 
spiral sculpture they twist and untwist with varying changes of 
moisture, and thus subserve the distribution of the spores. 

In a large section of genera, the Anemineae, a capillitium is 


In the Physaraceae the lime is aggregated in the sporangium in 
the form of granules ; but in the Didymiaceae, though, as in other 
Calcarineae, granular in the plasmodium stage, it assumes, when 
separating from the maturing sporangium, a crystalline form, being 
deposited on the sporangium wall either in clusters of crystals 
(Didymium and Spumaria, Fig. 13, g) or in discs with a radiating 
arrangement (Lepidoderma, Fig. 13, /t). It is clear that in this 
process the lime must be in a state of solution as it passes through 
the sporangium walls. 

The spores vary in diameter from 3-5 yu, (in Tubulina stipitata) to 
16-20 /x (in Licea pusilla) ; and the size is generally approximately 
uniform in each species. The surface may be smooth, tuberculated, 



FIG. 15. 

a, sporangia of Trichia varia, x 15 ; 6, one of the capillitium threads ; c, spores, x 160 ; <?, 
a spore of Hcmitrichia chrysospora, x nearly 600 ; c, sporangia of Arcyria incarnata ; in one the 
sporangium wall lias broken and the capillitium has expanded, in another the empty base 
alone remains, x 16 ; / and g, capillitium and spores of A. punicea, x 160. (a, d, and e, after 
A. Lister, 18.) 

or reticulated (Fig. 15, d) ; and the sculpture may be absent from 
one side of a spore, a peculiarity generally associated with the 
arrangement of the spores in clusters. 

Aethalia and Plasmodwcarps. In several species of Mycetozoa 
the sporangia, instead of standing apart, are more or less closely 
fused to form large compound bodies known as Aethalia, which 
present characteristic features of shape and structure. The identity 
of the individual sporangia may remain obvious or be entirely lost 
in the mature aethalia, but in the course of their development their 
compound nature is usually evident. 

In many cases (Fuligo, Fig. 16, Iteticularia, Lycogala) the proto- 
plasm Avithdraws from the peripheral portions of the sporangia, the 
walls of which collapse in consequence and together form a cortical 
layer, and a similar withdrawal of protoplasm from the basal 



region often gives rise to a spongy base to the aethalium, to 
which the name hypothallus has been loosely applied, though the 
structure is as distinct from the true hypothallus as is any other 
part of the supporting substance. 

Many Mycetozoa forming aethalia are closely allied to species 
with discrete sporangia. Thus Fuligo is an aethalioid form of 

Fio. 16. 

Aethalium of Fuligo septica. a, part of a ripe aethalium in section, showing the cortical 
layer, x 1. b, part of a section of the developing aethalium, showing the separate convoluted 
tubular sporangia_of which the aethalium is composed, x about 390. (After de Bary, 2.) 

Physarum, Spumaria of Didymium; and species in which the 
sporangia are usually distinct may assume an aethalioid form, as in 
the " confluent " variety of Stemonitis fusca. 

In some species the plasmodium does not become rounded off into 
distinct and symmetrical spor- 
angia in the spore-producing 
stage, but retains a diffused 
.and lobate form. In other re- 
spects maturation proceeds as 
in ordinary sporangia. These 
bodies are known as plas- 
modiocarps (Fig. 17). Aethalia 
appear to be formed by the 
fusion of sporangia, while 
plasmodiocarps are sporangia 
incompletely segregated. 

Plasmodiocarps are characteristic of some genera (Licea), but 
frequently occur together with completely -formed sporangia in 
the same species of others. 


The genus Ceratiomyxa (formerly known as Ceratium), the single 
representative of the Exosporeae, differs from the Endosporeae 

Fio. 17. 

The plasmodiocarp form of Diili/minm rffusum. 
x 15. (After A. Lister, 18.) 


in the relation of the spores to the supporting structures, and 

in the changes which occur 
when the spores are hatched 
(Fig. 18). 

The plasmodium inhabits 
rotten wood and emerges in 
cushion-like masses, which may 
become honeycombed with de- 
pressions or separate into dis- 
tinct antler-like branches. On 
its emergence it assumes the 
condition of an intimately 
anastomosing network of pro- 
toplasmic strands distributed 
through an abundant hyaline 
gelatinous substance, and at 
first exhibiting the characteristic 
rhythmic ebb and flow seen in 
the plasmodium of the Endo- 
sporeae. As the definitive 
shape is assumed, the proto- 
plasm leaves the interior and 
accumulates at the surface of 
the mass, at first as a close- 
set reticulum, and then as a continuous layer investing the 
gelatinous substance, though with a thin covering of the latter still 
external to it. The layer of protoplasm then separates into a- 
mosaic of polygonal cells (Fig. 18, b), each occupied by one of the 
nuclei of the plasmodium. The cells are at first in contact with 
their fellows at their margins, but they now draw apart, and each 
projects in the centre of the area which it occupied, beyond the 
contour of the lobe on which it lies, though still covered by the 
thin hyaline layer. As the projection increases its base becomes- 
constricted, and finally the cell, or young spore, containing the 
nucleus and all the protoplasm which occupied the polygonal area, 
is raised some distance above the general surface, invested by 
a thin covering, and supported on a slender stalk both furnished 
by the investing layer. Each spore now assumes an elliptical 
shape, secretes a firm colourless wall, and is ready to drop away. 1 

During the later stages of this process the gelatinous material' 
constituting the sporophore dries, and by the time the spores are 
ripe, forms a shrivelled, white mass of extreme tenuity (Fig. 18, a). 
According to Famintzin and Woronin (9), who first described the 
details of the life-history of Ceratiomyxa, the protoplasm emerges in 
the morning and the spores are ripe within twenty-four hours. 

1 For nuclear changes during spore-formation, cp. p. 66. 

FIG. 18. 

Ceratiomyxa mucida, Schroet. a, ripe 
sporophore, x 40 ; 6, maturing sporo- 
phore, showing the development of the 
spores, x about 100 ; c, ripe spore ; d, 
hatching spore ; e-h, stages in the develop- 
ment of the zoospores, x 800. (a and c-h 
after A. Lister, 18 ; 6, after Famintzin and 
Woronin, 9.) 


The spores, which at their formation are uninucleate (Fig. 1 8, c), 
are found, on hatching, to contain four bodies which are apparently 
nuclei (Fig. 18, d\ so it would appear that division of the nucleus 
occurs in the spore stage. When the spores are brought into 
water the contents emerges, becomes amoeboid, and successively 
constricted into separate lobes, two, four, and eight in number 
(Fig. 18, e-g). At the stage when eight lobes are formed each 
develops a flagellum (Fig. 18, h), and finally, becoming distinct 
from its fellows, swims off as a zoospore. It is evident that a 
further division of the nuclei must occur during this process. The 
zoospore subsequently enters the amoeboid stage, and the amoebae 
probably fuse to form plasmodia, as in the Endosporeae, though the 
process has not been followed in Ceratiomyxa. 

On comparing the somewhat incomplete details of this life- 
history with those of the Endosporeae, it seems clear that the 
abundant gelatinous substance in which the protoplasm is contained 
at the end of the plasmodium stage of Ceratiomyxa is, as Famintzin 
and Woronin pointed out, comparable Avith the secreted material 
which is converted into the supporting structures of the 
Endosporeae. In Ceratiomyxa the spores, instead of lying in a 
compact mass, contained in a sporangium, are distributed in a 
superficial layer, and the sporophore is accordingly disposed so as 
to offer an extensive surface for their support. 

The division of nuclei prior to spore-formation, found wherever 
the development has been followed in the Endosporeae, has not been 
seen in Ceratiomyxa, and as this process is frequently met with in 
other groups of Protozoa, its apparent absence here is remarkable. 
It is possible that this division is represented by the first of the 
nuclear divisions occurring within the spore ; in which case the 
spores of Ceratiomyxa would be comparable with the masses into 
which in the Endosporeae the protoplasm separates about the 
dividing nuclei before spore-formation, rather than with the spores 
of that group. If this comparison were established, however, the 
two following divisions which occur in Ceratiomyxa before the 
zoospores are formed would remain features peculiar to the genus. 1 


The other group here included with the Mycetozoa, the 
Sorophora, consists of forms the alliance of which with the 
Euplasmodida is somewhat remote. They live in decaying vege- 
tables and the dung of herbivorous animals. There is no flagel- 
late stage in the life-history, and it is in the form of amoebulae 
that the active phase, with growth and reproduction by fission, 
occurs. At the end of this vegetative phase, and only as a pre- 

1 Cf. the Postscript at the end of this article. 



liminary step to sporulation, the amoebulae draw towards their 
fellows in groups, which may be composed of many hundreds of 
units, but they maintain their individual distinctness and do not 
fuse to form a true plasmodium as in the Euplasmodida. Spore- 
production occurs in air, at the surface of the substance in which 
the vegetative phase has been spent. 

In Guttulina, as well as in the members of the Dictyosteliaceae, a 
remarkable differentiation occurs among the amoebulae forming the 
pseudoplasmodium, comparable with that characteristic of the 

organisation of the Metazoa. 
Some of the amoebulae secrete a 
firm membrane and become joined 
end to end to form a stalk (Fig. 
1 9, c and d), attached below to the 
substratum, and up this the other 
amoebulae climb and pass into the 
encysted condition at the top as 
a naked cluster of spores. In 
Didyostelium the stalk is long and 
simple ; in Folysphondylium it is 
branched (Fig. 19, d). 

Tlie supporting structures of 
the Sorophora are evidently of a 
different nature from those of the 
Euplasmodida, in which they are 
not cellular, but formed as secre- 
tions of the protoplasm. 

It is, of course, possible that 
the pseudoplasmodia of the Soro- 
phora may represent a stage in 
the evolution of the true plas- 
modium, which in the other group 
is such an important phase of the 
life -cycle; but it appears more 
probable that both Euplasmodida 
and the Sorophora are to be 
derived from some simple forms 
with a life-history resembling that 
of Protomonas or Bursulla among 
the Proteomyxa. 

Fio. 19. 

a and 6, Copromyxa protea, Fayod. a, a 
simple, b, a branched form of sorus, slightly 
magnified (after Fayod. ) c and d, Poly- 
sphondylium violaceurn, Brefeld. c, a young 
sorus, seen in optical section, with a mass 
of amoebae grouped round the stalk, and 
others still extended about the base, x 110. 
d, a sorus approaching maturity. The stalk 
has become compound. The lowest whorl 
of secondary sori is complete, those above it 
are in varying degrees of completeness, x 20. 
(After Brefeld. From Zopf, 24.) 

Two hundred and sixty -five 
species of the Euplasmodida are 
described in the British Museum Catalogue (18); Zopf (24) 
enumerated nine species of Sorophora, and Olive (20), more 
recently, twenty. 


The classificatory characters are mainly derived from the 
sporangia, the capillitium (when it is present), and the spores. 
Some species stand apart from their allies with great distinctness, 
but in many genera examples intermediate in character between 
the species are of common occurrence, and it is only by large 
experience of the frequency with which the forms, as they occur 
in nature, group themselves about certain centres that a correct 
idea of the species can be attained. 

The distribution of most species appears to be, so far as it has 
yet been determined, world-wide in the more humid parts of the 
temperate and tropical regions of the globe, where woodlands and 
forests offer conditions favourable to their existence a fact which 
is doubtless dependent on the ease with which the minute spores 
are carried in currents of air. 

No Mycetozoa have hitherto been met with in a fossil state, 
though from the degree of differentiation of the sporangia we cannot 
doubt that the group is of high antiquity, and has in past time, as 
at the present, played an important part in the disintegration of 
vegetable tissues. 

It is remarkable that no parasitic organisms are known to live 
on Mycetozoa, a fact which Stahl attributes to the readiness with 
which foreign bodies are cast out by the organisms in the plas- 
modial stage. 

In writing this account of the Mycetozoa constant reference has 
been made to de Bary's classical work (1-3), to the papers of 
Cienkowski (5-8), and to Zopf's treatise (24). But I wish especially 
to acknowledge my obligations to the work of my father, Mr. A. 
Lister, on their life -history and classification. So far as I have 
been able to speak of the biological aspects of the group from my 
own knowledge, it is mainly to the opportunities I have had in 
following this work that I am indebted. The proof-sheets of this 
article have been submitted to my father, and I feel that its- 
authority is greatly enhanced when I add, as he allows me to do r 
that the conclusions are in the main in accordance with his views. 


The contents of the spores develop, on hatching, into flagellate 
zoospores. Amoebulae completely fused to form the plasmodium, which 
is the dominant phase of the vegetative period. 

Spores developed within sporangia. 

Spores violet, or violet-brown. 


Sporangia provided with lime. 

ORDER 1. Physaraceae. 

Lime in minute, round granules. 

A. Capillitium a coarse network charged with lime throughout. 
Genus Badliamia, Berk. (Figs. 9 and 10). 

B. Capillitium a delicate network of threads with vesicular 
expansions tilled with lime-granules ( = lime-knots), a. Sporangia com- 
bined into a convolute aethalium. Genus Fuliyo, Haller (Fig. 16). 
P. Sporangia single, scattered, or aggregated, a, sporangium wall 
membranous. Genera Physarum, Pers. (Fig. 13, a). Sporangia sub- 
globose or in the form of plasinodiocarps. Physarella, Peck. Sporangia 
tubular. 6, sporangium wall cartilaginous throughout, or at the base 
only. Genera Cienkowskia, Rost. Sporangia in the form of plasmodio- 
carps ; Capillitium with free hooked branches. Craterium, Trent (Fig. 
13, d). Sporangia goblet - shaped or subglobose. Leocarpus, Link. 
Sporangia ovoid, glossy. 

G. Capillitium without lime -knots. Genera Chondrioderma, Rost. 
(Fig. 13, e). Sporangium wall of two layers, more or less combined. 
Trichamphora, Jungh. Sporangium wall of one layer, fragile ; sporangia 

D. Lime confined to the stalk and columella ; sporangium wall 
membranous. Genus Diachaea, Fries. 

ORDER 2. Didymiaceae. 

Lime deposited in the form of crystals or crystalline discs on the 
outer surface of the sporangium wall ; Capillitium without lime-knots. 
Genera Didymium, Schrader (Fig. 17). Lime in crystals ; sporangia 
simple. Spumaria, Pers. (Fig. 13, </). Lime in crystals ; sporangia united 
into an aethalium. Lepidoderma, de Bary. Lime in crystalline discs 
(Fig. 13, h) sporangia simple. 


Sporangia without deposits of lime ; Capillitium dark brown or violet 

ORDER 1. Stemonitaceae. 

Sporangia stalked, the stalk extending within the sporangium as a 
columella ; sporangium wall a single delicate membrane, often evanescent. 
Genera Stemonitis, Gleditsch (Fig. 1 4, a-e). Sporangium wall evanescent ; 
.Capillitium springing from all parts of the elongated columella, its ultimate 
branches forming a superficial net. Comatricha, Preuss. Like Stemonitis, 
but the branches of the Capillitium not forming a superficial net. Ener- 
thenema, Bowman. Sporangium wall evanescent ; columella reaching to 
the apex of the sporangium, where it forms a superficial expansion from 
which the capillitium springs. Lamproderma, Rost. Sporangium wall 
somewhat persistent, columella about half the height of the sporangium. 


Clastoderma, Blytt. Sporangium wall partly evanescent, persisting in the 
form of minute discs, at the tips of the rigid capillitium threads ; columella 
ehort or none. Echinostelium, de By. A minute colourless form with 
long stalks and a sparsely-branched spiny capillitium. 

ORDER 2. Amaurochaetaceae. 

Sporangia combined into an aethalium ; capillitium of irregular 
strands and threads, or complex. Genera Amaurochaete, Rost. Capil- 
litium of irregular branching threads. Brefeldia, Rost. Capillitium of 
horizontal threads, with many-chambered vesicles. 

Spores variously coloured, never violet. 


Capillitium absent, or not forming a system of uniform threads except 
in Alwisia. 

ORDER 1. Heterodermaceae. 

Sporangium wall membranous, beset with minute round granules, 
and (except in Lindbladia) forming a net in the upper part. Genera 
Lindbladia, Fries. Sporangia sessile, compacted or aethalioid, the wall 
not forming a net in the upper part. Cribraria-, Pers. Sporangia stalked ; 
sporangium wall with thickenings in the form of a delicate persistent 
net, expanded at the nodes. Dictydium, Sclirader (Fig. 14,/). Sporangia 
stalked ; sporangium wall with thickenings in the form of longitudinal 
ribs connected by delicate threads. 

ORDER 2. Liceaceae. 

Sporangia solitary, sessile or stalked ; sporangium wall cartilaginous ; 
capillitium and columella absent. Genera Licea, Schrader. Sporangia 
sessile, globose or in the form of plasmodiocarps. Orcadella, Wingate. 
Sporangia stalked, furnished with a lid of thinner substance. 

ORDER 3. Tubulinaceae. 

Sporangium wall membranous, without granular deposits ; sporangia 
tubular, compacted together. Genera Tubulina, Pers. Columella 
absent. Siphoptychium, Rost. A hollow pseudo- columella is present, 
connected by tubular extensions with the sporangium wall. Alvrisia, 
Berkeley and Broome. Sporangia stalked ; with tubular threads attached 
to the base and apex of the sporangium wall. 

ORDER 4. Reticulariaceae. 

Aethalia, with the sporangium walls incomplete, perforated, and 
forming a spurious capillitium. Genera Dictydiaethalium, Rost. 
Sporangium walls cap -shaped above and continued down to the base 
in four to six straight threads. Enteridium, Ehrenberg. Walls of 


convoluted sporangia forming a tissue of interarching bands. Reticularia, 
Bulliard. Walls of convoluted sporangia forming tubes and folds with 
numerous anastomosing threads. 

ORDER 5. Lycogalaceae. 

Sporangia forming an aethalium ; pseudo-capillitium consisting of 
branched colourless tubes, the remains of the walls of the fused sporangia. 
Genus Lycogala, Micheli. 

Capillitium a system of uniform threads. 

ORDER 1. TricMaceae. 

Capillitium threads with spiral or annular thickenings. Free or 
united into an elastic network. Trichia, Haller (Figs. 11, 12, and 15, a-c). 
Capillitium abundant, threads free, with spiral thickenings. Oligonema, 
Rost. Capillitium scanty, threads free, with imperfect spiral thickenings. 
Hemitrichia, Rost. (Fig. 15, d). Capillitium threads combined into a net- 
work, with spiral thickenings. Cornuvia, Rost. Sporangia in the form 
of plasmodiocarps ; Capillitium threads combined into a network, with 
annular thickenings. 

ORDER 2. Arcyriaceae. 

Capillitium combined into an elastic network with thickenings in the 
form of cogs, half-rings, spines, or warts. Genera Arcyria, Hill (Fig. 
15, e-/). Sporangia stalked ; sporangium wall evanescent above, persistent 
and membranous in the lower third. Lachnobolus, Fries. Sporangia 
sessile, clustered ; sporangium wall single, persistent, not thickened with 
granules. Perichaena, Fries. Sporangia sessile or in the form of plas- 
modiocarps ; sporangium wall double, at least at the base, the outer layer 
thickened with angular granules. 

ORDER 3. Margaritaceae. 

Sporangia normally sessile ; sporangium wall single, smooth, trans- 
lucent ; capillitium abundant, not consisting of separate threads, nor 
combined into a net. Genera Margarita, Lister. Capillitium profuse, 
long, coiled, and hair-like. Dianema, Rex. Capillitium of nearly 
straight threads, without spiral thickenings, attached at both ends to the 
sporangium walls. Prototrichia, Rost. Capillitium of fasciculate threads, 
attached above or below to the sporangium wall, and spirally thickened. 

Spores developed on the surface of sporophores. 

ORDER 1. Ceratiomyxaceae. 

Sporophores fragile and evanescent, branched ; spores white, borne 
singly on filiform stalks arising from the areolated sporophore. Genus 
Ceratiomyxa, Schroeter (Fig. 18). 



A flagellate stage is absent from the life -history. The amoebulae 
become aggregated prior to spore-formation, but do not fuse to form a true 
plasmodium. In the more highly developed genera some of the aggregated 
amoebulae are modified to form a stalk on which the remainder are borne 
after encystment in naked clusters (sori). 

ORDER 1. Guttulinaceae. 

The aggregation of amoebulae, prior to spore-formation, to form the 
pseudo-plasmodium, is incomplete in Copromyxa. The amoebulae have 
the Umax form, and the shape of the sori is indefinite. 

Genera Copromyxa, Zopf (Fig. 19, a and 6). Sori wart-like or 
spindle-shaped, 1-3 mm. high, formed on the surface of the nidus. None 
of the amoebulae are differentiated to form a stalk. On horse and cow 
dung. Guttulina, Cienk. Some of the aggregated amoebulae are dif- 
ferentiated to form a short stalk on which the sorus is borne. On decaying 
wood or horse-dung. 

ORDER 2. Dictyosteliaceae. 

A pseudo-plasmodium is formed prior to spore-formation. Some of 
the aggregated amoebulae are modified to form a stalk. The sori have a 
definite shape. Amoebulae with short pointed pseudopodia. Genera 
Didyostelium, Brefeld. Stalks unbranched, the spores without definite 
arrangement in the sori. On dung of herbivorous animals. A cram, van 
Tieghem. Spores arranged in rows, like strings of beads, at the ends of 
the stalks. On beer-yeast. Polysphondylium, Brefeld (Fig. 19, c and d). 
Sori globular, on branched stalks, which attain 1 cm. in length. On 


Since the foregoing account of the Mycetozoa was written papers .have 
been published, in part of a preliminary character, which appear to throw 
light on the nuclear history. 

In the Endosporeae, Fraulein H. Kriinzlin l has described a fusion of 
the nuclei in pairs, prior to the mitosis which precedes spore-formation, in 
the young sporangia of Arcyria, and this result is corroborated by Jahn. 2 
The number of chromosomes at this division Jahn believes to be sixteen 
(" 8 double chromosomes ") in Arcyria (at least double that which Jahn 
found in the division of the zoospore in other genera). In Fuligo Harper 3 
found the number to be twelve in the mitosis preceding spore-formation. 

1 " Zur Entwicklungsgescluchte der Sporangien bei den Trichien und Arcyrien," 
Arch.f. Protistenkunde, Bd. ix. (1907), p. 170. 

2 " Myxomycetenstudien 6. Kernverschmelzungen und Reduktionsteilungen," 
Eer. d. deutsch. botan. Gese.llschaft, Bd. xxv. (1907), p. 23. 

3 "Cell and Nuclear Division in Fuligo varians," Botanical Gazette, vol. xxx. 
(1900), p. 217. 


These authors suggest that the fusion of nuclei in the young sporangium 
is a long-deferred karyogamy, separated by the whole of the plasmodium 
stage, with its many nuclear divisions, from the plastogamy (the fusion of 
the amoebulae) by which the plasmodium originates. They thus regard 
the mitosis preceding spore-formation as the one nuclear division in the 
life-cycle in which the full ("somatic") number of chromosomes is present. 

Jahn (I.e.) and, subsequently, Olive 1 also state that a fusion of nuclei 
occurs in Ceratiomyxa prior to the formation of the spores. The fusion is 
followed by four according to Jahn, by two according to Olive, mitotic 
divisions, and the ripe spore is four-nucleated (not one-nucleated, as in- 
dicated above (Fig. 18, c)). 

It would thus appear that there are, at any rate, two mitotic divisions 
before spore-formation in Ceratiomyxa and only one in the Endosporeae. 
The spores are thus not strictly homologous in the Endosporeae and 
Exosporeae. That of Ceratiomyxa is more advanced than the spore of the 
Endosporeae in that at least two mitotic divisions subsequent to karyogamy 
have occurred (and the four nuclei thus arising are contained in the spore), 
but it is less advanced in that no cleavage of the protoplasm about the 
products of division has taken place. 


1. de Bary, A. Die Mycetozoen. Zeits. f. \viss. Zool. vol. x. (1860), p. 88. 

2. Die Mycetozoen. 2 e Auflage, Leipzig, 1864. 

3. Comparative Morphology and Biology of the Fungi, Mycetozoa, and 

Bacteria. Translation. Oxford, Clarendon Press, 1887. 

4. Butschli, 0. Protozoa, Abth. g, Sarcodina. Bronn's Thierreich, Bd. i. 

5. Cienkowski, L. Die Pseudogonidien. Priugsheim's Jahrbiicher, i. p. 371. 

6. Zur Entwickelungsgeschichte der Myxomyceten. Pringsheim's Jahr- 
biicher, iii. p. 325 (published 1862). 

7. - Das Plasmodium. Ibid. p. 400 (1863). 

8. Beitrage zur Kenntniss der Monaden. Arch. f. mikr. Anat. i. (1865), 

p. 203. 

9. Famintzin, A., and Woronin, M. Ueber zwei neue Formen von Schleimpilzen, 

Ceratium hydnoides, A. and Sch., and C. porioides, A. and Sch. Mem. de 
1'Acad. Imp. d. Sciences de St. Petersbourg, ser. 7, T. 20, No. 3 (1873). 

10. Greenwood, M., and Saunders, E. E. On the Role of Acid in Protozoan 

Digestion. Journ. of Physiology, xvi. (1894), p. 441. 

11. Jahn, E. Myxomycetenstudien 3. Kerntheilung u. Geisselbildung bei den 

Schwarmern von Stemonitis flaccida, Lister. Ber. d. deutschen botanischeu 
Gesellschaft, Jahrg. 1904, Bd. xxii. Heft 2. 

12. Krukenberg. Ueber ein peptisches Enzym im Plasmodium der Myxomyceten 

und im Eidotter vom Huhne. Uuters. aus d. physiol. Inst. in Heidel- 
berg, 1878, ii. p. 273. 

1 " Cytological Studies in Ceratiomyxa," Trans. Wisconsin Academy of Science, 
Arts, and Letters, vol. xv. (1907), pt. 2, p. 753 ; and "Evidences of Sexual Repro- 
duction in Slime Moulds," Science (N.S.), vol. xxv. (1907), p. 266. 


13. Lcinkcster, E. R. Article "Protozoa" in Encyclopaedia Britannica, 1891. 

14. Lister, A. Notes on the Plasmodiurn of Badhamia utricularis and 

Brefeldia maxima. Ann. of Bot. vol. ii. No. 5 (1888). 

15. On the Ingestion of Food Material by the Swarm-Cells of Mycetozoa. 

Journ. Linn. Soc. (Botany), vol. xxv. (1889), p. 435. 

16. - - On the Cultivation of Mycetozoa from Spores. Journ. of Botany, 

Jan. 1901. 

17. - On the Division of Nuclei in the Mycetozoa. Journal of the Linnean 

Soc. (Botany), xxix. (1893). 

18. A Monograph of the Mycetozoa. Brit. Museum Catalogue. London, 


19. Metschnikoff, E. Recherches sur la digestion intracellulaire. Annales de 

1'Institut Pasteur, 1889, p. 25. 

20. Olive, E. W. Monograph of the Acrasieae. Proc. Boston Soc. of Nat. 

History, vol. xxx. No. 6 (1902). 

20. Peiuird, E. ]5tude sur la Chlamydomyxa montana. Arch. f. Protisten- 
kunde, Bd. iv. Heft 2 (1904), p. 296. 

21. Plenge, H. Ueb. d. Verbindungen zwischen Geissel u. Kern bei d. 

Schwarmerzelleu d. Mycetozoen . . . Verb. d. nat.-hist. med. Vereins 
zu Heidelberg, N.F. Bd. vi. Heft 3, 1899. 

22. Stahl, E. Zur Biologic der Myxomyceten. Bot. Zeitung, .Jahrg. 42 

(1884), pp. 145, 161, and 187. 

23. Strasburger, E. Zur Entwickelungsgeschichte d. Sporangien v. Trichia 
fallax. Botanische Zeitung, 1884. 

24. Zopf, W. Die Pilzthiereo der Schleimpilze. Schenk's Handbuch der 

Botanik, 1887. 

25. Zur Kenntniss der Labyrinthuleen, einer Familie der Mycetozoa. 

Beitrage zur Physiologie u. Morphologic niederer Organismen. Heft 2 
(1892), p. 36, Leipzig. 

THE PEOTOZOA (continued) 


GYMNOMYXA (Homokaryota), with lobate or pointed unbranched 
pseud opodia without an axis and with one or more definite nuclei. 

In a large number of the characteristic genera of Lobosa the 
body consists of a small plastid of protoplasm protruding a few 
lobate pseudopodia by means of which a slow progression is 
effected, and exhibiting one nucleus and a contractile vacuole. 

In addition to these characteristic forms, however, other genera 
must be included in the same class in Avhich the body is protected 
by membranous or rigid shells (Thecamoebida), with radiating and 
pointed pseudopodia (Trichosphaerium, etc.), with two (Arcella), or 
numerous nuclei (Pelomyxa), and with no contractile vacuole 
(Endamoeba, etc.). 

In many Lobosa, such as Amoeba terricola (Penard [20]) and 
others, the superficial protoplasm secretes a membranous envelope 
through which the pseudopodia may be protruded or particles of 
food ingested. In Trichosphaerium the envelope is relatively 
thick, gelatinous in texture, and provided with a series of very 
delicate radiating spicules, mainly composed of carbonate of 
magnesia. Spicules similar to these are also found in the ecto- 
plasm of Amoeba pilosa (Cash), in which no true membrane is 
formed. In Dinamoeba (Leidy) the spicules occur in a hyaline 
jelly that surrounds the body. 

In the Thecamoebida a definite shell is formed through which 
the pseudopodia cannot penetrate. In this case the pseudopodia 
can protrude only through a definite and permanent mouth or 
pore in the shell, which it is convenient to call the pylome (Hartog). 

In some forms of Amoeba and in other genera there is 
often seen an apparent differentiation of the protoplasm into a 
clear outer layer, called the ectoplasm, and a more granular and 
more fluid central substance called the endoplasm. This appear- 
ance is more clearly defined when the protoplasm is very active 
and several pseudopodia are protruded. In the quiescent stages 
and conditions of life the ectoplasm usually disappears or becomes 
extremely attenuated, and in species or forms with only one or two 

1 By Prof. S. J. Hickson, M.A., F.R.S. 


pseudopodia it can be clearly observed only on the pseudopodia 
themselves (Fig. 12, 2). It seems probable, therefore, that in the 
Lobosa there is no true differentiation of the cytoplasm, and that 
the appearance known as ectoplasm is only due to the temporary 
withdrawal of metaplasmic particles from the superficial parts of 
the active cytoplasm. 

At the surface of an Amoeba there may always be seen a dark 
border which has the appearance of a very thin pellicle. This 
pellicle may be traced on the sides of the pseudopodia, but fades 
away towards their extremities, becoming extremely attenuated at 
the active terminal point. Immediately below this pellicle there 
is a layer of very hyaline ectoplasm. In carefully prepared sections 
the hyaline ectoplasm is found to be not strictly homogeneous, but 
to possess an alveolar structure similar in general characters to that 
of other forms of protoplasm. At the actual surface there is a 
single layer of alveoli, in which, as in artificially prepared oil foams, 
the sides vertical to the surface are parallel, or almost parallel, to 
each other, giving the appearance of a row of fine vertical striae. It is 
apparently this marginal alveolar layer which constitutes the pellicle. 

The movements of an Amoeba may be best interpreted on the 
basis of the alveolar hypothesis of the structure of protoplasm. 

The protrusion of a pseudopodium begins with a lowering of 
the surface tension of the marginal alveolar layer over a small area 
on the surface. This is followed by a flow of endoplasm towards 
the area of reduced surface tension. It has been suggested that 
the initial stages are accompanied by a rupture of some of the 
alveoli at the surface, which liberates a fluid the enchylema and 
that this causes a local diminution of the surface tension. It is 
possible that the release of enchylema may continue during the 
whole of the process of the protrusion of a pseudopodium, and 
stop when the pseudopodium comes to rest. During the active 
protrusion of a pseudopodium there may be observed a rapid 
centrifugal flow of endoplasm towards the peri- 
phery, called the axial stream. At the apex this 
stream spreads outwards like a fountain, and is 
continued as return currents on the surface. Similar 
fountain-like currents have been observed in the 
movements of various artificially prepared foams, 
but in the living protoplasmic pseudopodium the 
velocity of the return currents diminishes more FIG. i. 

rapidly and soon comes to rest (Fig. 1). In an Diagram to show 
Amoeba such as A. Umax, in which, as a rule, only 

one pseudopodium is formed, there is a reverse 
fountain current at the posterior end, the particles at 
the surface flowing towards the axis and joining in the axial stream 
flowing in the direction of the advancing pseudopodium. But in 


this case the actual posterior end is not involved in the current, and 
by the increase of surface tension becomes folded or wrinkled, giving 
sometimes an appearance of several small pseudopodia (Fig. 12, 2). 
In polypodious Amoebae similar reverse currents may be ob- 
served in retreating pseudopodia, and in areas of the body 
that are supplying materials for the axial streams of advancing 
pseudopodia. 1 

Nucleus. The nucleus of the Lobosa in its resting condition 
usually exhibits a well-defined membrana liniitans. The chromatin 
is in the form of a number of spherical or irregular particles frequently 
collected together round the periphery, leaving a more or less clear 
space in the centre. In some cases a very delicate network of 
fibrils has been observed, which is regarded as linin (Fig. 2). 

One or more nucleoli composed of a substance which differs 
chemically in some of its reactions from chromatin 
may or may not be present. 

In Paramoeba eilhardi there occurs a deeply 
staining body in proximity to the nucleus, which 
was termed by Schaudinn (25), who described it, 
the " nebenkorper " (Fig. 4, c). This body divides 
previous to the division of the nucleus, and the 
two parts take up a position at opposite poles of 
the spindle. This body is usually regarded as a "nucleolar cen- 
trosome." A body corresponding to this has also been found by 

FIG. 2. 

Nucleus of Pelomyxa. 
(After Bott.) 


ch, ' 

Fio. 3. 

Dividing nucleus of 
Amoeba Umax, m.l, the 
meinbraua liini tans of the 
nucleus ; c, the nucleo- 
lar centrosome ; eh, the 
chromosomes arranged 
iu an equatorial band. 
(After Vahlkampf.) 

FIG. 4. 

The resting nucleus 
(.V) and "nebenkorper" 
(c) of Paramoeba eilhardi. 
(After Schaudinn.) 

Fio. 5. 

The nucleus of the 
same species dividing. 
The "nebenkorper" (c) 
has divided into two 
parts, which occupy a 
position at the foci of the 
central spindle, eh, the 
chromosomes arranged 
in an equatorial band. 
(After Schaudinn.) 

Vahlkampf in the division of the nucleus of Amoeba Umax (Fig. 3), 2 
but in this case the nucleolar centrosome lies within the nuclear 

1 The subject of amoeboid movements has of recent years attracted the attention 
of many observers. The views expressed by Biitschli (Investigations on Microscopic 
Foams, etc., transl. by Minchin, 1894) have been opposed by Jennings (14), 
but Jennings' views have been more recently criticised by Rhunibler (23). 

2 For a discussion on the nature of these bodies, see Goldschmidt and Popoff, 
Archivf. Protist. viii., 1907, p. 321. 


Although the presence of a defined nucleus is regarded as one 
of the characters of the class, it has been shown that the nuclei 
sometimes disintegrate and discharge their, chromatin into the 
cytoplasm as scattered granules. This occurs as a result of 
starvation in Pelomym (Bott [2]), and as an antecedent to the 
formation of sexual or reproductive nuclei in Endamoeba. 

Chromidia. In addition to the chromatin contained within the 
boundaries of the nuclei, there may be present in the cytoplasm of 
many Lobosa irregular scattered granules or a fine network of a 
substance which gives the same reactions and is probably of the 
same nature as chromatin. 

In some cases, Difflugia (Fig. 6), the network entirely envelops 
the nucleus or nuclei, but in others it is separated from the nuclei, 
Arcella, Cochliopodimn, etc. (Figs. 19 and 
21), by a halo of clear protoplasm. 

These granules are called the 
chromidia, and the network is called the 
chromidial network (Fig. 6, ch). The 
chromidia may arise by the migration of 
particles of chromatin from the nucleus 
into the cytoplasm or by the disintegra- 
tion of nuclei, but it seems probable that 
in some cases they may arise de now 
in the cytoplasm. 

The fate of the chromidia is varied. 
They may either give rise to the nuclei 

nf <y;iTnpfp<3 nr nf <5\virm innvp<5 (Tpnirn 
'I gametes S (^eniW- 

v>/.?is\ or they may accumulate in groups b y the chromidial network (ch). r , 

* 9 n . . J i . * i pylome; th, theca wall. (After 

and give rise to new nuclei of the Hertwig.) 

ordinary type in the cytoplasm (Arcella, 

I'elomyxa), in which cases they are called Idiochromidia. Or, on 

the other hand, they may be associated with the assimilating or 

vegetative functions of the cytoplasm and disappear when their 

activity is exhausted, in which case they are called Trophochromidia. 

Refringent and Crystalline Bodies. In many Lobosa crystalline 
bodies and vesicles containing a strongly refracting substance or 
fluid occur in great numbers in the cytoplasm. Very often they 
are far more numerous and conspicuous during the stages and 
conditions of life when active feeding is in progress than in 
conditions of starvation or reproduction. They are usually 
regarded as of the nature of reserve food materials. 

In Amoeba dofleini, Neresheimer (18) found that the crystalline 
body, proteid in composition, is associated with a trophochromidium 
which is probably the active principal of its formation. Veley (34) 
has shown that the refracting bodies of Pelomym are proteid in nature. 

On the other hand, Zuelzer (35} has described the bodies 


Section through Difflugia sp. ? 
showing the nucleus (A') surrounded 


formed by the trophochromidia of Difflugia as carbohydrate in 
composition, but the crystalline and other bodies of Trichosphaerium, 

according to Schaudinn, give differ- 
ent reactions. 

Vacuoles. In nearly all the 
freshwater and marine Lobosa there 
is at least one contractile vacuole. 
In Pelomyxa and some of the Theca- 
moebida, however, contractile vac- 
uoles have not been found. The 
endoparasitic Amoebida have no 
contractile vacuoles. In addition 
to the contractile vacuole numerous 
non- contractile vacuoles containing 
a fluid of unknown constitution 

FIG. 7. 

re, refringent proteid bodies ; b, symbi- 
otic bacteria (Cladothnx) ; chr, scattered 
chromidia ;, water vacuoles. (After Bott.) 


occur j n t h e endoplasm. 

When a particle of food OCClirs 

in a non-contractile vacuole it. is 

usually called a food-vacuole, and the fluid in such vacuoles has 
been shown in some cases to be slightly acid in reaction and 
probably contains a digestive ferment. 

In Arcella and in other Thecamoebida vacuoles containing a 
gas are found within the shell. These vacuoles serve hydrostatic 

Reproduction Fission, Reproduction by fission has been 
proved to occur as a normal process in many of the genera of 
Lobosa. In Amoeba and allied genera the result 
of fission is a pair of equal -sized daughter 

r* a ~-\ 

Fio. S. 

Daetylosphaera polypodia, M. Schultze, in three successive stages of division. The stages 
indicated occupied fifteen minutes, a, nucleus ; b, contractile vacuole. (After F. B. 

Amoebae. In Pelomyxa, Trichosphaerium, and probably in other 
multi nucleated Gymnamoebida, fission may be unequal. 

In the Thecamoebida one of the individuals of the act of fission 
retains the shell, and the other sooner or later forms a new shell 
which is usually larger than that of the parent. 


The process of fission is usually preceded by division of the 
nucleus, or in the binucleate Amoebae of both nuclei. 

In some species (Amoeba binucleata and Paramoeba eilhardi, 
Schaudinn (Figs. 4 and 5), A. Umax, Vahlkampf, and Amoeba proteus, 
Awerinzew) the division of the nucleus shows some of the charac- 
ters of ordinary mitosis. The chromatin is collected together into 
a large number of short chromosomes arranged in an equatorial 
row. They then divide and travel in two equal parties along 
faintly stained and nearly parallel lines, supposed to be of 
the nature of linin, towards the opposite poles of the nucleus, 
where they unite to form the chromatin network of the daughter 
nuclei. The threads of the figure do not always converge at the 
poles to a focal point, and as a general rule it is doubtful whether 
structures exactly similar to the centrosomes of the metazoan nuclei 
occur. Centrosomes, however, have been described and figured 
in the division of the nuclei of Pelomyxa (Bott [2], Fig. 11, a). 

Notwithstanding the evidence of a primitive kind of mitosis in 
the division of the nuclei in these and other species, the division of 
the nucleus of Amoeba crystalligera, of A. hyalina, of Dactylosphaera 
polypodia, and of Endamoeba coli (Schaudinn) is amitotic. 

In Pelomyxa and Trichosphaerium fission usually consists in the 
pinching off of globules from the body, each containing a few 
nuclei. These globules rapidly assume the characters of the 
parent; they increase in size and the number of the nuclei is 
.augmented. This process may be regarded as a case of unequal 
fission or of gemmation, but it appears to differ from the equal 
fission of some species of Amoeba in the respect that antecedent 
division of the nuclei is not an essential preliminary to division of 
the cytoplasm. In a large multinucleate form of Amoeba proteus, 
Stole (31) has found that division of the nuclei may or may not 
take place before fission ; and in some cases some of the nuclei 
divide and others do not before an act of fission. 

Encystment and Spore-Formation. It is now known that many 
of the Gymnamoebida periodically undergo a process of encystment 
in which the pseudopodia are withdrawn, the body becomes more 
or less spherical, and one or more tough membranes are formed 
which entirely surround and protect the animal. In some cases 
these cysts appear to be of the nature of resting cysts (Amoeba 
Umax, Vahlkampf [33]), the organism emerging from the broken 
cyst-wall with the same characters it possessed previous to cyst- 
formation. The formation of resting cysts probably occurs in all 
the Thecamoebida. In many cases, however, the encystment is 
accompanied by complicated nuclear changes and divisions followed 
by division of the cytoplasm, and a swarm of minute spores that 
.are often very different in character from the parent form are 
hatched out when the cyst-wall breaks down. 



In the case of Endamoeba coli (Schaudinn [36]), for example, 
the uninucleate amoeboid form discharges all foreign bodies from 
its cytoplasm and becomes surrounded by a clear, soft, jelly-like 
envelope. Within the cyst-wall it divides into two equal parts 
each with a single nucleus, and these two parts remain separate 
for a considerable time. The two nuclei then fragment, their 
chromatin being scattered in the cytoplasm as isolated chromidia. 
The two nuclei are now reconstructed, but each reconstructed 
nucleus is relatively poor in chromatin. Each of these nuclei now 
divides into two by a primitive kind of mitosis ; one of them from 
each half-amoeba is rejected as a polar nucleus and the remaining 
one divides again. At this stage in the process the protoplasm 
contracts, the gelatinous membrane disappears, and the cyst 
is surrounded by a harder membranous wall. The daughter 
nuclei of this mitosis conjugate reciprocally with the daughter 
nuclei of the other half-amoeba, and each of the two zygote nuclei 
thus formed divides twice. The eight nuclei thus formed become 
the nuclei of eight amoebulae which escape from the cyst. 

In Amoeba proteus also, according to Scheel, division of the 
nucleus and cytoplasm takes place during the encystment, and 

FIG. 9. 

A, cyst of Amoeba proteus ; abc, cyst-wall ; d, gelatinous envelope ; K, F, nuclei ; 0, albu- 
minous bodies, x 300. (After Scheel.) B, cyst of Endamoeba blattae, with 25 nuclei. (After 

a swarm of small amoebulae emerge from it when the cyst breaks 
down. In this case, however, there is no evidence that any form of 
nuclear conjugation takes place during the encystment. 

Conjugation. Although the complete life-history of only a few 
species of the Lobosa has, at present, been fully worked out, the 
evidence is accumulating to justify the conclusion that a process of 
conjugation is an essential condition for the completion of the life- 
cycle in all forms. The process of conjugation has not yet been 
observed in Amoeba proteus or in any of its allies. Nuclear con- 
jugation accompanied by fusion of the cytoplasm occurs during, 
encystment in Endamoeba coli. 


In Pelomyxa (Bott [2]) amoeboid isogametes are discharged 
from the body with a nucleus formed in a manner that suggests 
that the number of the chromosomes is reduced (infra, p. 76). 
These gametes conjugate to form a zygote (Fig. 10), which may 
subsequently encyst. 

In Trichosphaerium (Schaudinn [26]) a large number of 
biflagellate isogametes escape from the cyst and by exogamous 
conjugation form zygotes which become amoeboid in character. 

Biflagellate isospores arise from the cystic stage of Paramoeba 
eilhardi, but there is no evidence, at present, to show that they 

In Centropyxis (Schaudinn [27]) heterogametes are formed 
which have a shell. After conjugation the zygote escapes from 
the shell and forms a new one like that of the adult individual. 

Life-History. The recent rapid advance in our knowledge of 
the life-history of Lobosa, due in large measure to the researches 
of Schaudinn and R. Hertwig, suggests that in all cases the 
developmental cycle that is passed through is both complicated and 

In order to illustrate the general character of these life- 
histories, four examples may be taken for description. 

Endamoeba coli is found in the upper part of the human large 
intestine, but unlike Endamoeba histolytica it does not appear to be 
the cause of or associated with any particular form of disease. It 
undoubtedly occurs in perfectly normal and healthy hosts. 

During the ordinary vegetative life in the intestine it multiplies 
by simple fission with amitotic division of the nucleus. Occasionally 
schizogony occurs, when the nucleus divides into eight by successive 
mitoses and each of these nuclei becomes the nucleus of a daughter 
amoebula. After a certain period of vegetative life, the normal 
duration of which has not been estimated, the uninucleated amoebae 
become encysted, and in that condition are passed into the lower 
part of the large intestine, and so to the exterior with the faeces. 
The complicated divisions and the conjugation of the nuclei during 
and antecedent to complete encystment have already been described. 
Many of the cysts undoubtedly perish, but the cysts with eight 
nuclei when swallowed by another host will give rise to eight 
amoebulae which infest the intestine of the new host. The cysts 
with more than eight nuclei that are sometimes found in the faeces 
are, according to Schaudinn, degenerating cysts, and never give rise 
to active amoebulae. 

In Trichosphaerium, a marine rhizopod with peculiar radiate 
pseudopodia and many nuclei, there are two phases in the life-cycle. 
In the first phase the gelatinous investment is armed with radiating 
apicules. It reproduces itself in this phase by simple binary or by 
multiple fission, the pseudopodia being previously Avithdrawn. In 


the second phase, in which the radiating spicules do not occur, 
reproduction -may also occur in a manner similar to that of the first 
phase, but at the conclusion of vegetative growth the pseudopodia 
are withdrawn, all foreign bodies and excreta are expelled, and a 
cyst is formed. The nuclei then divide rapidly by repeated mitoses 
to form an immense number of minute nuclei. These nuclei become 
the nuclei of minute biflagellate swarm-spores (gametes), which escape 
from the gelatinous investment of the cyst, and after conjugation 
give rise to small individuals of the first phase. 

In Pelomj/xa, a multinucleate freshwater rhizopod (Fig. 14), repro- 
duction is effected by simple or multiple fission during the vegetative 

period of life, but at certain times, 
after a complicated series of 
nuclear divisions in which a re- 
duction in the number of chro- 
mosomes occurs, uninucleated, 
heliozoan-like swarm-spores escape 
which conjugate to form a zygote, 
and this encysts. From the cyst 
a uninucleated amoebula escapes, 
which by growth and multipli- 
cation of the nucleus gradually assumes the typical Pelomyxa form. 

In the preparation of the nuclei for the formation of the gametic 
nuclei, a considerable part of the chromatin is discharged into the 
cytoplasm, and from that which remains eight chromosomes are 
formed on the equatorial band of a central spindle (Fig. 11, a). Two 
successive divisions take place, the first of which is regarded as a 
reduction division, and the 
second as an equation division. 
The chromatin of the four 
chromosomes of this last 
division collect together in 
two lumps, and a transparent 
globular vacuole appears in 
their immediate neighbour- 
hood. This vacuole gradually 
fills with minute granules 

Fio. 10. 

Zygote of Pelomyia palustris. a, encysted. 
I, after escape from the cyst. (After Bott.) 


FIG. 11. 

Nuclear formation in Pdomyxa, a, the spindle 
of the reduction division with eight chromo- 
somes, b, the nucleus (A T ) of the gamete forming 
in a clear vacuole. ch, the chromatin lumps of 
which rapidly increase in Size the last nuclear division. (After Bott.) 

and gives rise to the nucleus 

of the gamete (Fig. 11, b). The chromatin lumps at the same time 

dwindle and eventually disintegrate. 

In Centropyxis, one of the Thecamoebida, binary fission occurs 
by the protrusion and division of the protoplasm preceded by 
amitotic division of the nucleus. One portion of the divided proto- 
plasm with one nucleus returns to the old shell, the other forms a 
new shell but of a larger size. It does not seem certain Avhether 


the individual retained by the old shell is or is not capable 
of further reproduction, but the occurrence of an immense number 
of empty shells in cultures of Centropyxis and its allies suggests that 
it may die after one act of fission. The individual that has formed 
a new and larger shell, however, certainly divides again, giving rise 
by a similar process to a daughter individual with a still larger 
shell. When by these processes of fission the full size is reached, 
the nucleus degenerates, after giving rise to an expanded chromidial 
network which, with about two-thirds of the protoplasm, protrudes 
from the mouth of the shell, is pinched off, and escapes. The 
remaining one-third of the protoplasm and the degenerate nucleus 
that remain in the shell probably die. 

The escaped protoplasm may give rise to one of two broods of 
gametes. In one brood (the megagametes) the chromidia give rise 
to a nucleus and the protoplasm forms a shell ; in the other, after 
a nucleus is formed from the chromidia and a shell is formed as 
in the first brood, a division into four individuals (the microgametes) 
takes place, and each of these escapes and forms a small shell. 
Conjugation takes place between the larger and smaller individual 
gametes, and the zygote escapes to form a new shell like that of 
the parent. 

ORDER Gymnamoebida, 

The surface of the body either naked or provided with a 
thin flexible membrane through which the pseudopodia can be 

Genera Amoeba. The generic name Amoeba is often applied 
to any naked amoeboid organism without reference to its subsequent 
or antecedent history. As our knowledge of the natural history 
of the simpler Protozoa widens it becomes more evident that the 
generic name should be used only in a restricted sense. The limits- 
we place upon the use of the generic name can only be regarded 
as provisional. Further investigations may well prove that the 
species now included in the genus Amoeba, ought to be still further 
separated into subgeneric or generic groups. 

The characters of the genus may be summarised as follows : 
Solitary Gymnamoebida, with a few short blunt pseudopodia, a 
single contractile vacuole, and one or more nuclei. No membrane 
covering the body in the trophic phase of life. Freshwater or 

Nine or ten distinct species have been described from fresh 
water in this country (Cash). They are usually found in the mud 
at the bottom of ponds or creeping on submerged vegetation. 
Some of the rarer forms are found in Sphagnum bogs. One of the 
commonest species is Amoeba proteus (Fig. 12, 5), a species capable 
of considerable variation in form, but usually exhibiting several 


digitiform pseudopodia. In this species there may be either one or 
many nuclei. It may reach a size of 200 /A in diameter. A. guttula 
(Fig. 12, 4) is another very common species of small size, 30 /A, which 
shows slow undulating movements of the ectoplasm but rarely 
protrudes definite pseudopodia. In Amoeba Umax (Fig. 12, 2), which 
is slug-like in form, the end that is posterior in progression shows 
a fan -shaped arrangement of short ridges, due probably to the 

FIG. 12. 

Different species of freshwater Gymnamoebida. 1, Dactylosphaera radiosa, x 260. 2, 
Amoeba Umax, x 200. 3, Amoeba verrucosa, x 200. 4, Amoeba guttula, Duj., regarded as a young 
form of A. proteus by Leidy. 5, Amoeba proteus. 6, Amoeba (Ouramoeba) vorax, x 130. N, 
nucleus ; c.v, contractile vacuole ; F.v, food vacuole ; F, hyphae of a fungus. In Amoeba vorax 
some of the large diatoms (D, D) upon which it feeds and the approximate positions of the 
nucleus and contractile vacuole are shown. (1, 2, 3 from Cash ; 4, 5, 6 from Leidy.) 

wrinkling of the surface in the vortex of the retreating axial stream 
.{see p. 69). 

The marine Amoebae have not yet been carefully recorded. 
Amoeba crystalligera is often found in marine aquaria, and a species 
allied to the freshwater A. guttula has been found at Woods Hole 
in America. Amoeba fluida was found in sea- water aquaria in 
Freiburg by Gruber, and this with two other species were also 
found by him in the Gulf of Genoa. 


It may be regarded as extremely doubtful whether the forms 
that the Amoebae present really indicate true differentiation into 
definite species, or represent the varying influence of certain ex- 
ternal conditions acting upon one species, or, again, represent 
different phases in the life - history of one or more distinct 
species. Thus it has been observed that when the amoebae 
found on the surface of decomposing hay infusions are placed upon 
a slide, broad lobate pseudopodia begin gradually to be extended 
in various directions and the general form of Amoeba, proteus is 
assumed. After a time, when progression may be induced in one 
direction, the body becomes elongated and more or less pointed at 
the anterior end, so that the form becomes similar to that known 
as A. Umax. If the water be made very feebly alkaline the amoebae 
contract into a spherical shape with very short dentate pseudopodia, 
similar to A. guttula, and then protrude long pointed pseudopodia 
similar to those of Dadijlosphaera radiosa. 1 

The forms usually attributed to the genus Ouramoeba, Leidy, 
have been shown to be Amoebae in which fungal filaments are 
growing (Poteat [21]). The filaments arise from spores which are 
always situated in the neighbourhood of the contractile vacuole. It 
has been suggested that the fungus receives nourishment from the 
waste products of the amoeba. These filaments have been observed 
in Amoebae attributed to the species A. villosa, A. linucleata, and 
A. proteus. 

The life -history of no species of Amoeba has yet been fully 
worked out, but Calkins (7) has shown that Amoeba proteus 
normally passes through an early stage when the pseudopodia are 
relatively long and more pointed and similar to those of A. radiosa ; 
and Scheel (29) has proved that the uninucleate condition is 
succeeded by a multinucleate condition previous to encystment. 

Calkins suggests that the life-cycle of Amoeba proteus may be 
somewhat as follows : The zygote gives rise to a small radiate 
form, which develops into the uninucleate type-form. This 
encysts and by schizogony gives rise to uninucleate Amoebae, 
which develop into the multinucleate type-form. The multi- 
nucleate type-form encysts and gives rise to the gametes, which 
conjugate to form the zygotes. 

Paramoeba, Schaudinn. Several radiating pseudopodia. A well- 
defined chromatin body is present in tlie cytoplasm close to the nucleus. 
Swarm-spores with two flagella. P. eilhardi was found in a marine 
aquarium in Berlin. 10-90 /JL. P. hominis, a human parasite (p. 83). 

Dactylosphaera, Hertwig and Lesser (Fig. 12, 1), is distinguished from 
Amoeba by the numerous rigid pseudopodia, \vliich do not completely 
retract when at rest. Freshwater. Maximum 120 /*. 

1 Verworn, General Physiology, English translation, 1899, p. 184 ; and Dofleii), 
F., Archiv Prot. Suppl., 1907, p. 250. 



Lithamoeba, Lankester 1 (Fig. 13). Body discoid, pseudopodia lobular 
and hernia-like. A distinct pellicle covering the body, which ruptures 
for the protrusion of the pseudopodia. Freshwater. Maximum 125 p. 

Dinamoeba, Leidy. Pseudopodia long, conical, and acute. Body 
enveloped in a delicate hyaline jelly bristling with minute spicules. 
Bogs of New Jersey. 60-160 /A. 

The following genera were described by Frenzel (8, 9) from fresh 
water in the Argentine Republic : Chromatella, Stylamoeba, Saltonella, 
and Eikenia. 

Centrochlamys, Claparede and Lachmaun. The body covered with a 
thin, membranous, disc-shaped test through which the pseudopodia pro- 

Fio. 13. 

Liihamoeba diseus, Lank. A, quiescent; B, throwing out pseudopodia. c.?', contractile 
vacuole, overlying which the vacuolated protoplasm is seen ; cone, concretions insoluble in 
dilute HC1 and dilute KHO, but soluble in strong HC1 ; /, food particles ; n, nucleus. (After 

trude. No definite pylome. A single nucleus and several contractile 
vacuoles. Freshwater. 40-45 p.. 

Amphizonella, Greeff. Probably closely related to Centrochlamys. The 
body is usually invested by a supple membrane which, under some circum- 
stances, is itself surrounded by a transparent mucilaginous envelope. 
The pseudopodia are pushed through these membranes and withdrawn 
again without leaving any definite aperture. It has not been deter- 
mined whether the position on the test through which the pseudopodia 
protrude is definitely fixed or varies. These two last-named genera 
are undoubtedly closely allied to Corycia, Cochliopodium, and other 

Hyalodiscus, Hertwig and Lesser. The ectoplasm usually very thick, 
and sometimes exhibiting radiating lines. A creeping movement with- 
out pseudopodia frequently occurs. One or more inconspicuous nuclei. 
Freshwater. 40-60 //,. 

Trichosphaerium, Schneider. The structure and life-history of this 
genus has been fully described by Schaudinn (26). The body is in- 
vested by a gelatinous test perforated by many pores for the protrusion 

1 Lankester, Q. J. Micr. Sci. xix., 1879, p. 484. 



of long digitate pseudopodia ; several nuclei ; no contractile vacuoles. 
Zooxanthellae occur in the protoplasm. Marina 

Pelomyxa, Greeff. A remarkable genus of Gymnamoebida found in 
the mud of ponds and ditches, and distinguished by the presence of an 
enormous number of minute nuclei. Several species have been described. 
P. palustris, Greeff, P. villosa, Leidy, 
are frequently found in this country 
and are probably cosmopolitan. P. 
penardi, Rhumbler (22), was found 
at Gottingen. P. viridis has only 
been found in British India. 

They vary considerably in size, 
but when spread out in progression 
P. viridis may attain to a size of 8 
mm. in diameter, and the other 
species to 2 mm. 

The form of the animal is like 
that of an amoeba, and progress is 
effected by means of numerous 
blunt lobose, villiform, or some- 
times attenuate and anastomosing 
pseudopodia of very variable form 
and length. There is neither test FIG. 14. 

nor enveloping membrane. Pelomyxa palustris, Greeff. An example 

T , . with comparatively few food particles. (After 

In the ordinary vegetative con- Qreeff.) 

dition of Pelomyxa there are very 

many nuclei. Bourne (3) calculated that in a large specimen of P. viridis 
there may be 10,000 nuclei. In addition to the nuclei there are numerous 
minute scattered chromidia (Bott [2]) (Fig. 7). These chromidia may be 
clearly seen in the ectoplasm. The chromidia are formed by the chromatin 
discharged from the nuclei, and they never unite to form a chromidial 
network. In addition to the nuclei and chromidia, the cytoplasm contains 
refringent bodies of a proteid nature (Veley [34]), numerous symbiotic 
bacteria, food - vacuoles, and various water - vacuoles, and minute 

The refringent bodies appear to be waste materials and probably a 
by-product of metabolism, and are undoubtedly used as the food material 
of the symbiotic bacteria. They are sometimes ejected from the body, 
but in general the Pelomyxa relies on the bacteria as scavengers to 
clear its protoplasm of these bodies. The life-history of the symbiotic 
bacteria (Oladothrix pelomyxae) has been studied by Veley, who also 
determined the proteid nature of the refringent bodies by obtaining the 
characteristic reactions with (1) Millon's reagent ; (2) sugar and sul- 
phuric acid ; (3) the xanthoproteic test ; and (4) with caustic soda and 
copper sulphate. 

The green vesicles described by Bourne in P. viridis appear to be of 
the same nature as the refringent bodies, but stained with chlorophyll 

The protoplasm of all the species contains a number of vacuoles and 
vesicles, but none of them appear to be rhythmically contractile. 


Endamoeba}- 'The species of this genus are parasitic in the 
intestines of various animals. There is no contractile vacuole, and 
rarely more than one short pseud opodium is protruded. Endamoeba 
coli is commonly found in the human intestine. It is often present 
in perfectly normal health, and is not associated with or the cause 
of disease. The size does not exceed 50 p. 

Endamoeba histolytica is so similar in size and form to E. coli 
in some stages of its life-history that it has been regarded as the 
same species, but it is now known to have a different life -history 

and to be the active cause of certain 
'":::N forms of tropical dysentery. It is 
found not only in the ulcers of the 
intestinal mucous membrane, but 
also in abscesses of the liver accom- 
panying the disease. It penetrates 
the mucous membrane of the intes- 
tine and enters the submucosa 
(Dopter [42]). 
FIO. 15. The life -history of Endamoeba 

Endamoeba coli. A, a specimen with one 7)7e//i7<>;/?V/7 TIQO r>f Traf V>PPTI -fnllv 

nucleus in the resting condition. B,- a ntStOtyttCa Has not yet t 

specimen with two nuclei. (After Casa- worked OUt. It is very Similar 

grandi and Barbagallo.) . n T 

in size and appearance to L. con, 

but differs from it in the somewhat indefinite and variable 
character of having usually a more distinct hyaline ectoplasm. 
According to Lesage (43) the large cysts, similar to those of E. coli, 
20 ju, in diameter, are never found in this species. In E. histolytica 
the cysts are 3-6 //, in diameter. During the progress of the disease 
which it causes it is constantly changing its shape and position, and 
asexual reproduction proceeds rapidly by simple fission or multiple 
gemmation. Cyst-formation only begins when healing commences, 
never in the height of the disease. The encystment is preceded 
by the rapid discharge of chromidia into the cytoplasm, and then 
the nucleus degenerates and disappears. The chromidia then collect 
to form a chromidial network in the ectoplasm, and subsequently 
spherical bodies, the cysts, each surrounded by a yellowish-brown 
membrane and containing a portion of the chromidial network, are 
pinched off (Fig. 1 6, D). The rest of the life-history has not been 
followed, but it has been shown that when the cysts are given to 
cats they cause a dysenteric disease. 

Other species of Endamoeba have been described from the human 
intestines, but it is uncertain at present whether they are or are 

1 The account given of Endamoeba coli and E. histolytica is mainly taken from 
the important memoir of Schaudinn. This memoir is, however, not illustrated. 
For further information and for figures of Endamoeba coli the reader is referred 
to the memoir by Casagrandi and Barbagallo (38), and of E. histolytica to the 
memoir of Jiirgens (39) and other papers mentioned in the list of literature on 
p. 92. 


not associated with disease. Endamoeba undulans, Castellani (40), 
exhibits a peculiar amoeboid form, which occasionally protrudes a 
single pseudopodium. There is practically no distinction between 
the ectoplasm and endoplasm. The presence of a peculiar undulat- 
ing membrane running round one end of the body suggests that 
the species may have different affinities to the ordinary species of 
Endamoeba. 25-30 //,. Ceylon. Endamoeba iurai, Ijima (12), has 
been described from the human intestines in Japan. 

The species described under the name Parainoeba hominis by 
Craig (41) was found in the faeces of patients suffering from 


Fio. 16. 

KiK/'Uiioeba histolytica, Schaudinn. A, B, two specimens from a case of dysentery in a cat ; 
c, blood corpuscles being digested ; N, nucleus. (After Jiirgens.) C, specimen from human 
intestine with resting nucleus (N) and a single non-contractile vacuole. D, specimen giving 
rise by gemmation to a spore ; eh, chromatin of nucleus in the form of scattered chromidia ; 
sp, protoplasm of spore containing some chromidia. (C and D after Lesage.) 

severe diarrhoea in the Philippine Islands, associated with E. 
histolytica and other Protozoa. There appear to be three phases in 
the life - history : (1) an amoeboid phase, 15-25 p.; (2) a resting 
cystic stage, 15-20 //,; (3) a biflagellate phase, 3-15/z. Notwith- 
standing the general resemblance in its life-history to that of the 
marine Paramoeba eilhardi, it is difficult to believe that this species 
is rightly placed in the same genus. 

Endamoeba blattae is often found in the rectum of the common 
cockroach. In form it is similar to Amoeba Umax, but it seldom 
pushes out a single pseudopodium and has remarkably clear proto- 
plasm. It may be as much as 80 //, in diameter. Other species 
probably belonging to the same genus are found in the intestines 
.of mice and in the rectum of the frog. 

8 4 


It is difficult to determine at present the true nature of many 
of the amoeboid cells found in the pus and other fluids of patho- 
logical conditions, but the following are regarded as parasitic 
organisms : Amoeba urogenitalis, Amoeba kartulisi, 
Amoeba buccalis. 

Leydenia gemmipara is an amoeboid cell originally 
found by Lieberkiihn in the ascites fluid of malignant 
tumours. The endoplasm contains numerous fat 
spherules, remnants of red and white corpuscles, and 
numerous crystalline bodies. The most remarkable 
feature of Leydenia, however, is the presence of a 
definite contractile vacuole. Plastogamy frequently 
occurs, and reproduction is effected by fission and 
gemmation. There seems to be little doubt from 
the researches of Schaudinn that Leydenia is an in- 
dependent organism, but whether it should be placed 
with tne LoDOsa or with the Myxomycetes is not 


teria; c, at the an- 
terior pole granules 
are seen arranged in 
the direction of the 
protoplasmic cur- 

rents (After schu- 


The body is protected by a shell or test, which 
may be perforated by a hole the pylome or 
widely open on one side like a cap. The test is not perforated by 
the pseudopodia. 

The test of the Thecamoebida is composed of two sheaths 
an inner sheath, which is in the form of a thin continuous layer ; 
and an outer sheath, which is usually much thicker, and may be 
strengthened by the secretion of definite hard plates or by the 
adhesion of foreign materials of various kinds. The chemical 
constitution of the test is difficult to determine with accuracy, but 
it appears to consist of an organic matrix usually containing silica 
in larger or smaller proportions. The inner sheath of the test 
contains a small proportion or only traces of silica ; the plates and 
prisms of the outer sheath, such as we find in Quadrula and its 
allies, contain a much larger proportion of silica. The matrix 
which cements the plates of Quadrula together, and which fastens 
diatom shells, grains of sand, and other foreign bodies to the test of 
Difflugia, is an organic substance which also contains a trace of 
silica. In the plates of Quadrula irregularis calcium appears to 
take the place of silicon. 

There is no evidence of the occurrence of chitin in the tests of 
any Thecamoebida, but a substance allied to keratin may occur in 
some cases (Awerinzew [1]). 

In the Cochliopodiidae the shell is thin and flexible. It is 
usually marked by minute punctuations arranged in definite rows 
or more irregularly distributed. When more highly magnified 


these punctuations appear to be globular in shape, but their precise 
nature has not yet been determined. 

In Quadrula the outer sheath consists of a series of square 
plates cemented together by the matrix. These plates can be 
raised to a high temperature without destruction of their form. 
When boiled for a long time in 10 to 20 per cent KHO, they 
are dissolved but leave behind a fine granular residue which 
probably represents the inorganic components of the plates. In 
Nebela the plates are discoidal, and in other genera irregular in form. 

The diatom or desmid shells, the grains of sand or glass, and 
other foreign bodies that are found fastened to the outer sheath of 
the test of Difflugia (Fig. 20) and its allies are not adventitiously 
placed, but are caught and definitely arranged in position by the 
animal (Rhumbler). There can be little doubt that Difflugia exercises 
a deliberate choice of the particles it uses for shell purposes, and 
to a certain extent the character of the foreign particles and their 
arrangement can be used for racial or specific distinctions. 

In the Arcellidae the outer sheath is composed of hexagonal or 
irregular prisms (Fig. 1 8), some of which, situated at regular 
intervals, are rather longer than the others and 
project on the surface as round knobs or bosses. QcOnxcnnnmj 
The prisms are cemented together by an extremely FIG. is. 

thin matrix. Section through the 

The cytoplasm of the Thecamoebida is often BSSSttEB 
arranged in three zones. The cytoplasm of the som . e of ^ hich project 

, , . -i i- -i r i i . -it irregular intervals 

pseudopodia and ot the region of the pylome is as shallow bosses on 
usually remarkably hyaline and the granulations Awerin U zew?)' 
extremely fine. In the middle zone it is more 
coarsely granular, and contains the contractile vacuoles, food- 
vacuoles, crystalline bodies, excreta, oil-globules, etc. In the zone 
next to the fundus of the shell is usually found the nucleus or 
nuclei and the sickle-shaped or more irregularly disposed chromidial 
network. In the Arcellidae, however, the arrangement is somewhat 
different from this (p. 86). 

The pseudopodia are probably subject to considerable variation 
in shape and number according to external conditions. In the 
Difflugiidae there may be only one long finger-like pseudopodium 
extended to a length double that of the shell, or there may be 
three or four shorter pseudopodia, or occasionally as many as seven 
protruded at the same time. In Heleopera the number of pseudo- 
podia appears to be constantly more numerous than in other genera 
of the family. 

In some species of Arcellidae and Cochliopodiidae a membranous 
expansion of the cytoplasm sometimes protrudes from the pylome. 
Very little is known concerning the contractile vacuoles of the 
Thecamoebida, as the thick opaque test interferes considerably with 


the observation of it in the living animal, but it seems probable that 
one or more contractile vacuoles are present in all genera. 

Nucleus. For a considerable period in the life-history of Arcella 
there are two large oval nuclei, from 0'015-0'02 mm. in diameter, 
which are usually situated some distance apart, near the periphery 
of the cytoplasm. More rarely three or even four of these 
relatively large nuclei may be found. These nuclei are derived by 
the karyokinetic division of the primary single nucleus of the young 
Arcella. Each nucleus contains a single large ("008 mm.) nucleolus, 
which apparently consists mainly of chromatin, but is otherwise 
clear and transparent (Fig. 21). 

In other Thecamoebida (Diffiugia 1 and Centropyxis} there is 
usually only one nucleus during the corresponding phase of the life- 
history, and this exhibits a coarse reticulum of chromatin with 
numerous nucleoli distributed through it. 

The chromidial network of Arcella is in the form of an 
irregular band or ring at the periphery of the cytoplasm, which 
sends lobate processes or branches in the direction of the central 
protoplasm. These processes are sometimes pinched off from the 
peripheral ring, and appear as isolated patches of the chromidial 
network in the central cytoplasm. 

In Centropyxis the chromidial network is in the form of a thick 
sickle-shaped band lying in contact with the convex aboral 
extremity of the body. Sometimes this band envelops the 
nucleus, but neither in Centropyxis nor in Arcella does the nucleus 
come into contact with the network, being always surrounded by a 
halo of clear protoplasm (Fig. 21). In some forms of Difflugia 
the chromidial network is in contact with the nucleus (Fig. 6) ; 
in D. globosa and others, however, there is a clear space between the 
nucleus and the chromidial network as in Centropyxis, but in 
these cases strands of the chromatin seem to .connect the nucleus 
with the network. 

In another phase of the life -history of Arcella there are 
numerous nuclei. The number is very variable, from 5 to 39, but 
in a great many cases there are about 25. These secondary nuclei 
are formed by the concentration of granules of chromatin of the 
chromidial network, which become rounded off and surrounded by 
a nuclear membrane. The larger the number of nuclei, the smaller 
they are. When very numerous these nuclei are not more than 
0'009-0 - 01 mm. in diameter. As the secondary nuclei are formed, 
the two or three primary nuclei degenerate and disappear. 

When a certain number of secondary nuclei have been formed, 

they divide by karyokinesis. This karyokinesis is a preparation for 

the process of fission. One half of the nuclei resulting from the 

karyokinetic division remain at the periphery, the remaining half 

1 According to Zuelzer there are 10-30 nuclei in D. urceolata, Carter. 


migrate towards the centre of the protoplasm. It is probably this 
central party of nuclei that, with their surrounding protoplasm, 
protrude from the pylome of the shell and give rise to the daughter 
Arcella in the process of fission. 1 

In Centropyxis (Schaudinn [27]) the formation of secondary 
nuclei previous to fission does not occur. When fission is about to 
take place, a considerable portion of the protoplasm protrudes from 
the pylome, assumes the inverted form of the parent, and develops a 
shell. The nucleus remains in that part of the protoplasm which 
at this stage only half fills the shell of the parent Centropyxis. When 
the daughter shell is formed the nucleus increases to nearly double 
its former size, the nucleolus dwindles in size, and numerous minute 
chromosomes are formed. These changes are followed by the 
formation of a spindle, the arrangement of the chromosomes in an 
equatorial plate, and subsequently by nuclear division. One of the 
nuclei thus formed passes into the daughter individual and the other 
remains in the parent. 

While these changes in the nucleus are taking place, the 
chromidial network divides into a great number of chromidia, which 
collect round the two nuclei in equal proportions and pass with 
them into the resultant individuals. 

Encystment. The formation of resting cysts occurs in Arcella, 
Centropyxis, Nebela, Diffluyia, and probably in all the other 
Thecamoebida (Martini [16]). 

In Centropyxis, Schaudinn found that cj'sts are formed when 
external conditions are unfavourable, such as in cases of desiccation, 
scarcity of food, etc. In such cases the food particles, diatom 
shells, excreta, a considerable proportion of the water, and any other 
non-essential contents of the protoplasm, are ejected, while the 
cytoplasm, with the contained chromidial network and nucleus, 
contracts into a ball and is surrounded by a cyst- wall. 

At the end of encystment the cyst - wall disintegrates, the 
protoplasm swells up to its former size, and the normal processes 
of life are continued. It does not seem probable in this case 
that encystment has any connexion whatever with the sexual 

In Arcella, however, according to Hertwig (11), a reduction 
in the number of the nuclei takes place, and it is suggested that 
the process of conjugation may occur during this period of encyst- 
ment, in a manner similar to that which occurs in Actinosphaerium. 1 

In Difflugia urceolata (Zuelzer [35]) a process of encystment occurs 
in the late autumn, and is accompanied by a destruction of a great 
many of the old nuclei. Before the cysts rupture in the spring the 
contents break up into a number of uninucleate secondary cysts, 
but the history of the secondary cysts has not been followed. 

1 See Note, p. 93. 


Plastogamy. A process of the temporary or permanent fusion 
of two or more individuals has been observed by Schaudinn (27) 
in Centropyxis, and by Zuelzer (35) in Diffiugia. urceolata, and probably 
occurs in other Thecamoebida. In Centropyxis two individuals may 
join together plastogamically and produce a daughter individual 
with two nuclei and two chromidial networks, or if three individuals 
join together they produce a daughter individual with three nuclei 
and three chromidial networks. In some cases, the daughter 
individual produced by the plastogamy has an abnormal shell and 
the two nuclei and chromidial networks fuse together. In other 
cases, again, only one of the individuals gives rise to a daughter 
individual, and that is of the normal type. 

In Difflugia urceolata a process of plastogamy occurs in which the 
nuclei and chromidial networks remain passive, when external con- 
ditions become unfavourable, but this appears to be antecedent only 
to disintegration. In the autumn, however, the protoplasm of one 
of the two participants in a plastogamic union passes into the shell 
of the other, and more rarely a process of plastogamy occurs in which 
the nuclei and chromidial network of both individuals are active, but 
definite fusion of nuclear elements has not been observed. At the 
end of this plastogamic fusion the empty shell may become firmly 
fixed to the shell containing the fused individuals, giving rise to 
the twin- shells so often found in cultures of these creatures 
(Rhumbler [22]). The meaning of the different forms of plasto- 
gamy in the Thecamoebida is not clear, but there is no evidence at 
present that they represent any phase of the true sexual process. 

The only observation of a true conjugation in the order is that 

described by Schaudinn, in which 
definite heterogametes are formed 
and conjugate (p. 77). 1 


usually thin and supple, with a 
flexible margin, shaped like a cap, 
limpet shell, or helmet. Pylome 
widely open. 

The genera included in this family 
have close affinities with some of the 
Gymnamoebida. The shell is not 
perforated by the pseudopodia, but in 
Cochliopodium it often assumes many 
CoMiopodiun pellutidum, Hert. and different shapes according to the 

Less, a, nucleus, surrounded by a halo of conditions of the animal, and in some 

species usually attributed to the genus 
(G. adinophorum and G. digitatum) it 

entirely surrounds the body and is perforated by the pseudopodia, the 

1 See Note,, p. 93. 

Fia. 19. 

Chr midial 



apertures being closed again when the pseudopodia are withdrawn. 
Cochliopodium, Hert. and Less., then, is the connecting-link between the 
two orders. In Corycia, Dujardin, the test is supple and membranous, but 
the pylome remains open. In Pseudochlamys, Clap, and Lach., the shell is 
shaped like that of a limpet, but is very flexible, and the margin of the 
pylome may in the retracted condition be inflected to form a shelf like 
the velum of a medusa. In 
Parmulina, Penard, the test is 
in the shape of a cup or bowl. 
In Hyalosphenia, Stein, the test 
is rigid except at its margin. 

Tests usually globular, or flask - 
ehaped with a narrow pylome. 
Outer sheath of the test with 
hard plates, or with adherent 
foreign particles, or with both. 

Dijfluyia, Leclerc, is a genus 
which exhibits a great many 
varieties of form, some of which 
are very common. The shell 
is usually flask - shaped, and 
consists of a tough double 
membrane to which various 
foreign bodies, such as diatom 
shells, sponge spicules, sand- 
grains, etc., are cemented. The 
pseudopodia are rarely more 
than two or three in number, 
digitiform and blunt, but some- 
times frayed at the extremities. 
Some of the larger varieties are 
over 0'5 mm. in length. 

Centropyxis, Stein ( = Echi- 
nopyxis, Clap, and Lach.), is 

related to Difflugia, but the \J FIG. 20. 

Bhell is usually discoidal Or Aj Diffiu{ ,ia pyrifwmis, Perty, with very large 
oval, With the pvlome excentric diatom shells attached to the theca. B, test of 
. . r _ . Quadrula symmetrica, Wallich. C, Lecquermsia 

in position. It IS covered spiralis, Ehr. D, diagram of test of Pontigulasia 

irre^ularlv with forpitm mr irlcisa > Rhumbler, showing the collar (co) and bridge 
reign par- (b) E) vjew of the bridge (6) of Pmitigu iasia from 

tides, and sometimes exhibits above. (A-C after Leidy ; D, B after Penard.) 
two or three short spines. 

Pontigulasia, Rhumbler, and Cucurbitella, Penard, are distinguished 
by the presence of a short collarette round the pylome. In Pontigulasia 
(Fig. 20, D and E) a broad flat bridge runs across the base of this collarette 
and divides the pylome into two apertures. In Lecquemisia, Schlumberger 
(Fig. 20, C), the shell is cornuate or slightly spirally twisted. The genera 
Quadrula, Nebela, and Heleopera form shells with siliceous plates and are 
not usually decorated at all with foreign particles. Quadrula, F. E. 


Schultze, is a common and widely distributed genus, with a shell of vari- 
able shape, but distinguished by its regular pavement -like arrangement 
of square or oblong plates (Fig. 20, B). Nebela, Leidy, is related to 
Quadrula, but the plates of the shell are round, oval, or even irregular in 
outline. In some species the shell is strengthened by adherent diatom 
shells. In all species of this genus particles of "fat" of a pale blue or 
yellow colour occur normally in the protoplasm. Similar particles also 
occur in Difflugia and other genera, but are not so constant or characteristic 
as they are in Nebela. 

The shell of Heleopera, Leidy, is provided with square or oblong 
plates as in Quadrula, but they are usually irregularly or untidily 
arranged. The pseudopodia of this genus are more numerous than in 
the others of the family, and are sometimes slightly branched. 

In Phryganella, Penard, the shell is covered with adventitious particles, 
as in Difflugia, but the pseudopodia are more numerous, more delicate, 
frequently branched, and occasionally amalgamated at the base to form a- 
membranous web. It appears to be related to Pseudodifflugia, Schlum- 
berger, which is usually regarded as a member of the Order Gromiidea r 
of the Foraminifera. As it is quite impossible to draw a definite line of 
distinction between organisms with a few fine blunt pseudopodia such as 
are characteristic of the Difflugiidae and those with filamentous branching 
pseudopodia such as are characteristic of the Gromiidea, there is a group 
of genera occupying an intermediate position between the Rhizopoda and 
the Foraminifera. 

The principal genera of this group are : 

Cryptodifflugia, Penard ; Pseudodifflugia, 1 Schlumb. ; Diaphwodon,^ 
Archer ; Platoum, 1 F. E. Schultze ; Clypeolina, Penard ; Nadinella, Penard; 
Frenzelina, Penard ; Campascus, 1 Leidy ; Cyphoderia, 1 Schlumb. 

Family ARCELLIDAE. Shells plano-convex in shape, marked by a 
very fine hexagonal pattern, not supported 
by adventitious particles. 

Arcella, Ehr. This is a common and 
widely distributed gemis. The shells of 
the common species A. vulgaris vary from 
80-140 p. in diameter, and like those v of 
most of the species of Arcella are charac- 
terised by their brown colour. The flattened 
side of the shell is usually depressed and 
perforated at the centre by the pylome, 
FIO. 21. which is less than one-third the diameter 

Arcella vulgaris, Ehr. a, shell ; of the shell. From the pylome there 
b, protoplasm within the shell ; c, . ,-, f , ' j , , 

lobose pseudopodia ; e, one of the project three or four, rarely more, digitate 

marginal vacuoles ; d, d, nuclei sur- pseudopodia. Situated in the ectoplasm, 

rounded by a halo of clear proto- x . . . , . 

plasm. (After Lankester.) and usually arranged in a circle round the 

pylome, there is often seen a series of 

vacuoles, which probably serve a hydrostatic function. They may fuse 
together to form a single large excentric vacuole, and this may collapse 
after the manner of a contractile vacuole. 

1 Cf. Treatise on Zoology, Part I. Fasc. II. pp. 140-141. 


Arcella is common in bogs and stagnant water, but is occasionally 
found in clear running water. 

Pyxidicula, Ehr., differs from Arcella in having a large gaping pylome. 
The surface of the shell is ornamented with numerous minute tubercles. 
20-50 /*. The genus is comparatively rare and little known. 


1. Awerinzcw, S. Die Structur und die chemische Zusammensetzung der 

Gehause bei den Stisswasserrhizopoden. Arch. Prot. viii., 1906, p. 95. 

2. Bott, K. Ueber die Fortpflanzung von Pclomyxa palustris. Arch. Prot. 

viii., 1906, p. 120. 

3. Bourne, A. (r. On Pelomyxa viridis n. sp. Q. J. Micr. Sci. xxxii., 1891, 

p. 357. 

4. Butschli, 0. Investigations on Microscopic Foams and on Protoplasm. 

Translated by E. A. Miiichin. Black, 1894. 

5. Untersuclmngen liber Structure!!. 1898. 

6. Calkins, G. N. Marine Protozoa from "Woods Hole. U.S. Fish. Comm. 

Bull. 1901, p. 413. 

7. Evidences of a Sexual Cycle in the Life-History of Amoeba proteus. 

Arch. Prot. v., 1904, p. 1. 

8. Frenzel, J. Untersuchungen iiber die mikroskopische Fauna Argentiniens. 

Arch. mikr. Anat. xxxviii., 1891, p. 1. 

9. U^ber einige merkwiirdige Protozoen Argentiniens. Zeitschr. wiss. 

Zool. liii., 1892, p. 334. 

10. Goldschmidt, R. Die Chromidien bei Protozoen. Arch. Prot. v., 1904, 

p. 126. 

11. Hertwig, R. Ueber Encystirung und Kernvermehrung bei Arcella vulgaris. 

Fest. Kupffer, 1899. 

12. Ij-ima. New Rhizopod of Man. Annot. Zool. Jap. 1898, p. 85. 

13. Jennings, If. S. Contributions to the Study of the Behaviour of the 

Lower Organisms. Washington, 1904. 

14. The Movements and Reactions of Amoeba. Biol. Centralbl. xxv., 

1905, p. 92. 

15. Lei/den, E., and Schaudinn, F. Leydenia gemmipara. S.-B. Akad. Berlin, 

vi., 1896. 

16. Martini. N. Beobaclitungcn an Arcella vulgaris. Zeitschr. wiss. Zool. 

Ixxix., 1905, p. 574. 

17. Mesnil, Felix. Chromidies et questions connexes. Bull. Inst. Pasteur, 

iii., 1905, p. 313. 

18. Neresheimer, E. Ueber vegetative Kernveranderungen bei Amoeba. Arch. 

Prot. vi., 1905, p. 147. 

19. Penard, E. Faune rhizopodique du bassin de Leman. 1902. 
20. Amibes a pellicule. Arch. Prot. vi., 1905, p. 296. 

21. Potent, W. Leidy's genus Ouramoeba. Science, viii., 1898, p. 778. 

22. Rhumbler, L. Beitrage zur Kenntniss der Rhizopoden. Zeitschr. wiss. 

Zool. Hi., 1891 ; and same journal, Ixi., 1896. 

23. Zur Theorie der Oberflacheiikriifte der Amoeben. Zeitschr. wiss. 

Zool. Ixxxiii., 1905, p. 1. 


24. Schaudinn, F. Ueber die Theilung von Amoeba binucleata. S.-B. Ges. 

Naturf. Berlin, 1895, p. 130. 

25. Ueber den Zeugungskreis von Paramocba eilhardi. S.-B. Ak. 

Berlin, 1896, p. 31. 

26. Untersuchungen iiber den Generationswechsel von Trichosphaerium 

sieboldi. Anhang z. d. Abh. Ak. Berlin, 1899. 

27. Untersuchungen iiber die Fortpflanzung einiger Rhizopoden. Arb. 

kais. Gesundheitsamte, xix., 1903, p. 547. 

28. Neuere Forschungen iiber die Befruchtung bei Protozoen. Verb. 

deutsch. Zool. Ges., 1905, p. 16. 

29. Schcel, C. Beitrage zur Fortpflanzung der Amoeben. Fest. Kupffer, 1899, 

p. 569. 

30. Schubotz, H. Beitrage zur Kenntniss der Amoeba blattae und Amoeba 

proteus. Arch. Prot. vi., 1905, p. 1. 

31. Stole, A. Ueber die Teilung des Protoplasmus in mehrkernigen Zustande. 

Arch. Entw. Mech. xix. p. 631. 

32. Plasmodiogonie. Arch. Entw. Mech. xxi., 1905, p. 111. 

33. Vahlkampf, E. Beitrage zur Biologic und Entwickelungsgeschichte von 

Amoeba Umax. Arch. Prot. v., 1905, p. 167. 

34. Veley, V. H. A Further Study of Pelomyxa. J. Linn. Soc. Zool. xxix., 

1905, p. 374. 

35. Ziielzer, M. Beitrage zur Kenntniss von Difflugia urceolata, Carter. 

Arch. Prot. iv., 1904, p. 240. 

Some of the more important recent papers on the parasitic Amoebae and 

36. Schaudinn, F. (No. 27.) 

This paper contains the most important but uniUustrated account of 
the life-history of Endamocba coli and Endamoeba histolytica. 

37. Schuberg, A. Die parasitische Amoben des menschlichen Darmes. Kritische 

Uebersicht. Centrbl. Bakter. xiii., 1893, pp. 598, 654, and 701. 

These papers contain a critical account of the literature of Amoebiasis 
up to the year 1893. 

38. Casagrandi, Q., and Barbagallo, B. Entamoeba hominis s. Amoeba coli, 

Lbsch. Ann. d' Igiene sperimentale, v., 1897, fasc. i. 

This paper contains a full account of Endamoeba coli and its occur- 

39. Jilrgens. Zur Kenntniss der Darmamoben und der Amoben -Enteritis. 

Verbff. a. d. Gebiete Militarsanitatswesens, 1902, Heft 20, p. 110. 
This paper contains a good account of Endamoeba histolytica. 

40. Castellani, A. Protozoa in Human Faeces. Centralbl. Bacter. xxxviii., 

1905, p. 66. 

41. Craig, C. F. A New Intestinal Parasite of Man, Paramocba hominis. 

Amer. J. Med. Sci. cxxxii., 1906, p. 214. 

42. Dopter, C. Sur quelques points relatifs a Faction pathogene de 1'Amibe 

dysenterique. Ann. Inst. Pasteur, xix., 1905, p. 417. 

43. Lesage, A. Culture de 1'Amibe de la dysenteric des pays chauds. Ann. 

Inst. Pasteiir, xix., 1905, p. 9. 


44. Mugliston, T. C., and Freer, G. D. An Undescribed Form of Ulceration of 

the Large Intestine, probably of Amoebic Origin. J. Trop. Medicine, viii., 
1905, p. 113. 

45. Afusgrave, W. E., and Clegg, M. J. Amoebas : their Cultivation and 

Etiological Significance. J. Inf. Diseases, ii., 1905, p. 334, and Publ. 
Bureau Govt. Lab. Manila, xviii., 1905, p. 5. 

References to the general treatises of Butschli, Braun, Calkins, Cash, Doflein, 
Jfartog, and Lang will be found on p. 13. 

NOTE. In a recent paper W. Elpatiewsky (Arch. Prot. x., 1907, p. 441) has 
shown that Arcella produces small amoeboid gametes (megamoebae and micra- 
moebae) which conjugate and form a zygote. 

THE PEOTOZOA (continued) 


THE Eadiolaria are purely marine Gymnomyxa, specialised for 
pelagic life. The body is usually spherical or conical, and emits 
radiating thread-like pseudopodia. The cytoplasm is subdivided 
by a perforated membranous " central capsule " into a central mass 
and a voluminous mantle. The nucleus, which may be single or 
multiple, is confined to the intracapsular region, which is also the 
seat of reproductive changes, the extracapsular mantle being con- 
cerned with flotation, feeding, stimulation, and excretion. A siliceous 
skeleton is usually present, and may take the form of spicules, 
shells, and tubes in a variety of delicate and exquisite constructions. 
In one division (Acantharia) the skeleton consists, so far as is known, 
of strontium sulphate. In most Radiolaria peculiar nucleated yellow 
corpuscles are found in abundance. They are regarded either as 
" symbiotic algae " or as Peridinians. Multiplication by fission is 
known in a few cases ; more commonly reproduction by spore- 
formation has been observed. 


As an introduction to the description of the class the following 
account of Thalassicolla has been drawn up. 

Thalassicolla is a spherical gelatinous Protozoon from 3-5 mm. 
in diameter. In the warmer waters of the great oceans it occurs in 
vast swarms that float passively at the surface but also descend 
into deeper water during the reproductive phase. It ranges for some 
forty degrees of latitude on either side of the equator, diminishing 
in numbers towards these limits. It is abundant in the Faroe 
Channel (Wolfenden, Fowler), and a stray specimen is now and 
then recorded from our coasts (Delap [40]). 

Thalassicolla consists of two parts a central or medullary region 
and a thick outer or cortical layer. The two are separated by the 
central capsule. 

The intracapsular mass consists of a large centrally placed 
nucleus embedded in cytoplasm, heavily laden with concretions, 

1 By F. W. Gamble, D.Sc., F.R.S., Manchester University. 



coloured fat, and reserve products. The extracapsular cytoplasm 
is composed of (1) a thin, black, fatty assimilative layer or matrix 
immediately outside the central capsule ; (2) a frothy mass of 
mucilaginous and vacuolated substanpes secreted by interstitial 
cytoplasm and forming the so-called "calymma" ; and (3) of fine 
radiating pseudopodia which arise from the matrix and extend 
freely into the water beyond the gelatinous bubbly layer. The 
wall of the central capsule is perforated by minute, evenly dis- 



FIG. 1. 

Thalassicolla (Thalassophysa) pelagica, Haeckel. x 25. CK, central capsule ; EP, extra- 
capsular protoplasm ; al, alveoli, carbonic acid-holding vacuoles in the mucilaginous calymma 
secreted by the protoplasmic network ; ps, pseudopodia. The minute unlettered dots are the 
" yellow cells." (After Lankester.) 

tributed pores, and through these the intra- and extracapsular 
cytoplasm are continuous. 

If the central capsule is shaken out of its calymmal covering 
and kept under suitable conditions, its contents are capable of 
regenerating the extracapsular cytoplasm within a week (Verworn 
[14:]). The first sign of this process is the protrusion of new radial 
pseudopodia, which are completed in twelve hours. The basal 
ends of these processes form or secrete a layer the matrix that 
invests the central capsule, and their radial extensions secrete the 
calymma. Finally, vacuoles make their appearance in the jelly 
and the matrix becomes pigmented. In short, the extracapsular 


protoplasm and its secretions are the product of intracapsular 
activity. The extracapsular cytoplasm, on the other hand, has 
no such regenerative power. When detached from the capsule it 
loses its form, the pseudopodia contract, the vacuoles burst, and 
the plasma undergoes granular degeneration. For this and other 
reasons we may speak of the extracapsular cytoplasm as the ecto- 
plasm, and the intracapsular plasma as the endoplasm ; for although 
the pseudopodia are common to both and interconnect them, yet 
the mass of the calymma is a secretion specialised for contact with 
the outer world, and performs other important functions, whilst the 
endoplasm is less directly concerned with the immediate physiological 
needs of the animal. 

Bionomics. The most remarkable physiological characteristic 
of Thalassicolla is its paucity of reaction. It possesses no power 
of active movement, and responds only to two forms of external 
stimulus vibration and heat ; and to one internal agency, namely, 
the stimulus of reproduction. Under the influence of wave-action 
Thalassicolla sinks till a calm stratum is reached, and then after a 
time ascends to the surface. Towards small variations of temperature 
it remains as inert as toward all conditions of illumination that 
have so far been tried ; but a long-continued application of tempera- 
tures above 30 C. or below 2 C. induces a descent from the 
surface of the sea-water, and this is followed by the death of the 
animal. The onset of maturity is also correlated with a descent 
into deep water. During the nutritive phase and under normal 
variations of vibration, heat, and light, the station of TJialassicolla is 
at or near the surface of the sea. 

This station is ensured for it by the development of the calymma. 
The mass of this veil is made up of a mucilaginous secretion containing 
fluid-vacuoles, and is enclosed in a delicate cytoplasmic investment, 
the quantitative proportion of which is in minimal relation to the 
bulk of its secretions and vacuolar fluid. By careful observation, 
weighings, and experiment, Brandt (24) has shown that the vertical 
movement of Thalassicolla is due to the formation and expulsion 
of vacuolar fluid. The hydrostatical requirements of the case 
demand that, for flotation at the surface, the density of this fluid 
should be that of water saturated with carbonic acid. As the 
physiological probability is in favour of this conclusion, we may 
accept Brandt's view as in all likelihood correct. Assuming 
this, then, the explanation of passive descent and ascent is easy. 
In calm weather and through a considerable range of temperature 
the interchange of fluid between the vacuole and the sea is gradual, 
and the slight wave-motion reinforces the calymma by acting as a 
stimulant. Thus we may assume the balance of loss and gain, and 
with it the surface position, are maintained. But the movements 
of larger or more frequent waves, or the extremes of experimental 


temperature, cause contraction of the calymmal plasma. The pseudo- 
podia are withdrawn, the vacuoles burst, and the animal descends 
until the calmer zone enables it to reform its calymma and recharge 
its vacuoles, upon which it ascends. No " contractile vacuoles " 
are present, but their place is taken by these fluid-spaces in the 

Food. The food of Thalassicolla consists of Copepods, Diatoms, 
Infusoria, and probably also of Peridiniae. These organisms adhere 
to the surface of the Kadiolaria by contact with its sticky pseudo- 
podia. They are subsequently enfolded by a plasmic web and 
carried into the deeper part of the calymma. Here a digestive 
vacuole is formed, and the ingested organism becomes converted 
into a granular mass, which is disseminated, by division of the 
digestive vacuole, throughout the ectoplasm. An accumulation of 
debris may sometimes be found in the denser layer enveloping 
the central capsule, and there is little doubt that the products of 
digestion do not stop here but are carried into the endoplasm, for it 
is known that a streaming movement occurs along the pseudopodia 
that connect the inner and outer cytoplasm through pores in 
the capsular wall. Once inside the capsule, the food material is 
probably synthesised into the fatty or proteid masses that con- 
stitute reserves. The endoplasmic globules of fat are usually 
coloured with a pigment that varies according to the species of 
Thalassicolla under consideration. The other reserves take a con- 
cretionary form and recall starch grains in their stratified composi- 
tion, though not in their reactions. They lie in vacuoles filled 
with a proteid, and are still imperfectly known (Fig. 2, A, Cone.). 

Yellow Cells. The ingestion of solid food is, however, not 
essential to the life of Thalassicolla for at least several months. If 
kept in water that has been taken from the open sea and com- 
pletely filtered, Thalassicolla will live for at least six months without 
showing retrogressive changes beyond a shrinkage of calymmal 
volume. Brandt, who has carried out experimental studies on 
these organisms for many years, states (24) that if comparable 
batches are maintained in such filtered water in darkness and in 
light, the illuminated ones alone survive. He infers that Thalas- 
sicolla under these conditions lives upon food which is in some way 
elaborated under the influence of light ; and in point of fact such 
a substance starch does exist in the ectoplasm. It occurs both 
free in the capsular layer and imbedded in the substance of certain 
corpuscles which are scattered through the calymma and are 
known as the " yellow cells." The significance of these cells or 
" zooxanthellae " is, in Brandt's view, a nutritive one. 

That these bodies are independent organisms living in association 
with Thalassicolla and are not part of it was proved by Cienkowski (6). 
They are spherical structures '015 mm. in diameter, and consist of 



a cellulose wall, two chloroplasts marked by diatomin or an allied 
pigment, a pyrenoid, starch of hollow and solid varieties, and a 
nucleus. During the life of their host the zooxanthellae multiply 
by transverse fission. After its death they pass into a "palmella 
state " characterised by a mucilaginous jelly, and from this they 
often escape as active biflagellated zoospores. 

Such zooxanthellae are frequent though not constantly present 
in Thalassicolla. In T. nudeata they may be plentiful, scarce, or 
absent. In most species they occur unfailingly ; sometimes in the 
outermost jelly, sometimes in radial masses throughout the calymma, 
or aggregated round the capsule, but never within it. The adapta- 
tion of their host to surface life meets the requirements of the 
yellow cells for light, oxygen, and no doubt other unascertained 
demands, with the result that the association has been regarded as 
one of mutual advantage, as a case of symbiosis. 

The more recent work of Famintzin (13) has, however, tended 
to diminish the importance of the part which, according to Brandt, 
is played by the abundant starch of the yellow cells in nourishing 
their host. According to the later writer, the nutrition of Thalassi- 
colla is mainly derived from ingested organisms, and is only aided 
by the yellow cells in as far as these bodies are digested by the 
ectoplasm. It is probable, though exact demonstration is as yet 
wanting, that in some diffusible state exchange of material does take 
place from zooxanthella to host without involving the death and 
digestion of the former. Such a relation, however, does not explain 
the presence of the yellow cells in Radiolaria. 1 

Respiration. The researches of Vernon (22) have shown that 
gelatinous or mucilaginous pelagic animals have a high rate of 
destructive metabolism, and that the amount of oxygen absorbed 
per unit of dry body -weight is further increased in the smaller 
animals as compared with the larger members of the same group, 
and in those of warmer seas as against their cold-water relatives. 
The maximum relative absorption of oxygen amongst inverte- 
brate planktonic animals is reached, according to Vernon, in the 
Radiolaria. Collozoum, a near ally of Thalassicolla, has the highest 
coefficient of all invertebrates, equivalent to forty times that of 
the frog ; and although it is desirable to have further evidence 
before accepting this startlingly high figure, yet the evidence of other 
pelagic forms points unmistakably to a very large consumption of 

The recent work of Putter (43) has emphasised the singular 
nature of Protozoon respiration. It has long been known that 
many of these organisms can live for a time as anaerobes, and it 
now appears that intramolecular respiration obtains in a great 
number of cases and to an unexpected extent. Fresh energy is set 
1 For a discussion of the origin of the association see below, p. 129. 


free during the decomposition of reserve materials, and so long as 
the waste products evolved in this process are removed, respira- 
tion will continue in a medium deprived of free oxygen. Such a 
view enables us to consider the reserve materials of Radiolaria 
as of respiratory as well as of nutritive significance. It is not 
improbable that the respiration of the endoplasm (in which these 
fatty and stratified reserves occur) is of a different character from 
the more violent exchange which seems to occur in the ectoplasm. 

In connection with destructive metabolism we may summarise 
our view on the nature of excretory processes in Thalassicolla. That 
carbonic acid and nitrogenous excreta are formed in abundance 
seems certain from the rapid destruction and regeneration of the 
calymma and its vacuoles, but there is no accumulation of excretory 
substances such as occur in most Rhizopods. It is suggested, on 
the basis of experiments with Turbellaria (Gamble and Keeble [41]), 
that this absence of excretory matter is due to the activity of the 
yellow cells, which are attracted to their host chemotactically and 
from which, by the uric acid or urea therein, they derive their nitrogen. 
In the same way such a view affords an explanation of the associa- 
tion of zooxanthellae with Radiolaria, and of the apparently con- 
comitant absence of excretory granules. Additional proof of the 
correctness of this view lies in the fact that such granules occur 
massively and constantly in one division of the Radiolaria (the 
Phaeodaria or Tripylaria), and that in this division, and in this 
only, zooxanthellae are as constantly absent. 

Reproduction. In addition to multiplication by simple fission 
(25a), Thalassicolla has two true reproductive processes, which, how- 
ever, never occur in the same individual. These processes con- 
cern the formation of spores, which are of two kinds, isospores 
And heterospores. A given Thalassicolla is, therefore, isosporous or 

When the reproductive period ensues, the protoplasm and its 
contents undergo a metamorphosis, which results in the transforma- 
tion of the endoplasm into a mass of flagellated spores, in the dis- 
integration of the calymma, and the separation of the sporulating 
capsule from its envelope. The relatively heavy capsule descends 
to a depth of 300-400 metres, its wall bursts, and its spores are 
liberated. In the case of isospores these bodies are of uniform 
shape and size (Fig. 2, D) ; in the case of heterospores (L, M) two 
varieties occur, of which the larger are not only twice the size of 
the smaller ones, but possess other distinctive characters which are 
given below. 

The formation of isospores in Thalassicolla nucleata proceeds as 
follows (Brandt [26]). The nucleus and endoplasm undergo a 
series of changes. The chromatin, previously coiled up in a thick 
thread, becomes evenly granular, and the nucleoplasm acquires an 

almost homogeneous and doubly refractive character, and becomes 
irregular in shape as its membrane disappears. By what appears 
to be amitotic division the nucleus fragments into a large number 
of equivalent pieces, each of which behaves as an independent 
nucleus, and by further division these nuclei become disseminated 
through the endoplasm. Around each nucleus the cytoplasm con- 
denses to form an ovoid mass, which is differentiated at the nuclear 
pole into two cilia. Meantime the reserve materials of the endo- 
plasm become subdivided and apportioned, so that each isospore 
contains a few granules of fat and a crystalloid. These changes 
may be followed on the accompanying figures (Fig. 2, A-D). 

The development of heterospores in Thalassicolla proceeds in a 
different manner and from distinct individuals. The first step is 
the formation of a nuclear figure. A clear achromatic vesicle 
(centrosome, Brandt, 1905) arises in the nucleus and becomes 
surrounded by granular radiations, upon which the thick bent 
chromatin threads arrange themselves as in Fig. 2, E. The centro- 
some now shifts towards the margin of the nucleus, and the more 
peripheral chromosomes become lumpy and slightly vacuolated. 
The nuclear wall softens, and through it, at one pole, pass the 
centrosome and a few apical chromatin granules. Subsequently the 
nuclear sap escapes over the entire periphery of the nucleus, 
together with much of the granular nuclear matrix, into the sur- 
rounding endoplasm. The chromatin threads fragment and the 
fragments become associated with segregated masses of fine nuclear 
granules to form organised nuclei, Avhich divide mitotically. During 
this process the nuclei are carried outwards in increasing numbers 
towards the wall of the central capsule, where they become 
arranged in columns, until almost the whole of the original nucleo- 
plasm is used up. The most remarkable features of this organising 
process is that the developing nuclei are of two sizes, which are 
severally aggregated in the peripheral columns. Meantime the 
endoplasm and its reserves have been mobilised. The former is 
converted into cylinders around the mega- or micro-nuclei, and 
within these cylinders the fat and crystalloids become fragmented 
and distributed. Finally, by subdivision of these nucleated masses 
colonies of mega- and micro-spores arise. Both are biciliate, and in 
comparison with isospores minute, and divided by a groove into a 
reniform shape. The microspores are from O'OOS to O'Ol mm. in 
length, the megaspores O'Ol 6 to O'Ol 7. The microspores have a 
deeply staining granular nucleus and a cytoplasm free from inclu- 
sions except for one or two minute crystalloids. The megaspores, 
on the other hand, possess a nucleus poor in chromatin, and their 
cytoplasm is crowded with refringent corpuscles. Both forms of 
heterospore have the same ciliary mechanism (Fig. 2, L). From 
one point in the groove two long cilia arise, one of which works 


FIG. 2. 

The development of isopores and heterospores in Thalassicolla nudeata. (After Brandt, 1905.) 
A-C, isospore-fonnation, xlOO. The large nucleus (N) breaking up into spore nuclei (N. Isp). 
1), an isospore (x 2000); Cone, stratified concretions lying in proteid vacuoles. E-K, hetero- 
spore - formation, x 100. E, nuclear membrane collapsing. Nuclear figure and one intra- 
nuclear centrosome. F, diffusion of nucleoplasm (A'w) outwards. G, organisation of second- 
ary nuclei (Ao). H and K, segregation of these nuclei to form heterospore nuclei. L, mega- 
spores. This figure shows the two flagella arranged like those of a Dinoflagellate. M, micro- 
spores. L, M, x 1000. 



horizontally and is coiled round the body of the spore, the other 
projects freely outwards and backwards. Consequently, as these 
minute structures dart or vibrate, they rotate unceasingly about 
their long axis, the whole mechanism and display recalling those 
of certain Peridiniae. 

The further history of the iso- and heterospores is unknown. 
Brandt's recent attempts (26) to obtain conjugation between spores 
of the same and of different individuals have been as futile as those 
of earlier observers. If, however, we may judge by the analogy of 
other Protozoa, and in particular by the life -history of Tricho- 
sphaerium (Schaudinn [42]), we may presume that the heterospores 
are male and female gametes, and that the isospores are asexual indi- 
viduals. But on this question, as on the further one of a suggested 
alternation between isosporous and heterosporous generations of 
Thalassicolla, we still lack information. 

1, central capsule of Thalassicolla nucleata, Huxley, in radial section, x 100 ; a, the 
large nucleus (Binnenblaschen) ; 6, proteid vacuoles of the intracapsular protoplasm con- 
taining concretions ; c, wall of the capsule (membranous shell), showing the fine radial pore- 
canals ; d, chromatin substance of the nucleus. 2, 3, Collozoum inerme, J. Miiller, two different 
forms of colonies, of the natural size. 4, central capsule from a colony of Collozoum inerme, 
showing the intracapsular protoplasm and nuclei, broken up into a number of isospores, each 
of which encloses a crystal of strontium sulphate ; c, yellow cells lying in the extracap.sular 
protoplasm. 5, a small colony of Collozoum inerme, magnified 25 diameters ; a, alveoli 
(vacuoles) of the extracapsular protoplasm ; b, central capsules, each containing besides proto- 
plasm a large oil-globule. 6-13, yellow cells of various Radiolaria. 6, normal yellow cell ; 
7, 8, division with formation of transverse septum ; 9, a modified condition according to 
Brandt; 10, division of a yellow cell into four; 11, amoeboid condition of a yellow cell from 
the body of a dead 'Sphaerozoon ; 12, a similar cell in process of division ; 13, a yellow cell the 
protoplasm of which is creeping out of its cellulose envelope. 14, Heliosphaera inermis, Haeck., 
living example, X400; a, nucleus; 6, central capsule; c, siliceous basket-work skeleton. 
15, two isospores of Collozoum inerme, set free from such a central capsule as that drawn in 4; 
each contains a crystal 6 and a nucleus a. 16, two heterospores of Collozoum inerme, of the 
second kind, viz. devoid of crystals ; and of two sizes, a megaspore and a microspore. They 
have been set free from central capsules with contents of a different appearance from that 
drawn in 4. o, nucleus. 17, Actinomma asteracanthion, Haeck., x260 ; one of the Peripylaria. 
Entire animal in optical section, o, nucleus ; b, wall of the central capsule ; innermost siliceous 
shell enclosed in the nucleus ; c 1 , middle shell lying within the central capsule ; c 2 , outer shell 
lying in the extracapsular protoplasm. Four radial siliceous spines, holding the three spherical 
shells together, are seen. The radial fibrillation of the protoplasm and the fine extracapsular 
pseudoppdia are to be noted. IS, Amphilonche messanensis, Haeck., x 200; one of the Acan- 
thometrida. Entire animal as seen living. (After Lankester.) 


The Radiolaria may be derived from such an organism as 
Thalassicolla by (1) fission and the formation of a colony of similar 
or dimorphic individuals imbedded in a voluminous communal jelly 
(Sphaerozoa or polyzoic Radiolaria) ; (2) by differentiation of the 
openings of the central capsule from its evenly porose condition 
(Peripylaria) to a radially segregated oligo-porose type (Acantharia), 
to a single pore-plate at one pole of the now asymmetrical capsule 
(Monopylaria), or to a single main aperture and two lateral ones 
(Tripylaria) ; (3) by differentiation in the ectoplasm of skeletal 
spicules and shells of the most diverse forms, which only in the 
Acantharia invade the endoplasm. 


Amongst the most primitive Radiolaria are the Physematiidae 
and the allied families Thalassicollidae, Thalassophysidae, etc. In 
all these forms the hydrostatic jelly is so well developed as to give 
the term Collodaria to the order formed by them. In the first 
family, however, the vacuoles elsewhere found in the ectoplasm are 
endoplastic products, no stratified nutritive concretions are found, 
and yellow cells are absent. The skeleton, if present, consists 
merely of scattered spicules. These organisms belong to the 
surface strata of the ocean and are phosphorescent. Their life- 
history falls into well-marked nutritive and reproductive phases. 
The early nutritive stage was erected by Haeckel into a special 
genus Actissa, which Brandt has shown to be a phase of growth 
that occurs in at least two of the five families. The later nutritive 
stage differs in few characters from that of Thalassicolla. The Phy- 
sematiidae afterwards pass into an isosporous reproductive phase ; 

FIG. 4. 

1, Lithocircus annularis, Hertwig ; one of the Monopylaria. Whole animal in the living 
state (optical section), a, nucleus ; 6, wall of the central capsule ; c, yellow cells ; d, per- 
forated area of the central capsule (Monopylaria). 2, Cistidium ine.rme, Hertwig ; one of 
the Monopylaria. Living animal. An example of a Monopylarion destitute of skeleton, a, 
nucleus ; b, capsule wall ; c, yellow cells in the extracapsular protoplasm. 3, Carpocanium 
diadema, Haeck. ; optical section of the beehive-shaped shell to show the form and position of 
the protoplasmic body, a, the tri-lobed nucleus ; b, the siliceous shell ; c, oil-globules ; d, the 
perforate area (pore-plate) of the central capsule. 4, Coelodendron gracillimum, Haeck. ; living 
animal, complete ; one of the Tripylaria. a, the characteristic dark pigment (phaeodium) 
surrounding the central capsule b. The peculiar branched siliceous skeleton, consisting of 
hollow fibres, and the expanded pseudopodia are seen. 5, central capsule of one of the 
Tripylaria, isolated, showing a, the nucleus ; 6, c, the inner and the outer laminae of the 
capsule wall ; d, the chief or polar aperture ; e, e, the two secondary apertures. 6, 7, Acan- 
thometron Claparedei, Haeck. 7 shows the animal in optical section, so as to exhibit the 
characteristic meeting of the spines at the central point as in all Acanthometrida ; a, small 
nuclei ; b, a parasite (Amoebophrya) ; c, wall of the central capsule ; d, extracapsular jelly ; 
e, peculiar intracapsular yellow cells. 8, Spongosplinera streptacantha, Haeck. ; one of the 
Peripylaria. Siliceous skeleton not quite completely drawn on the right side, a, the spherical 
extracapsular shell (compare Fig. 3 (17)), supporting very large radial spines which are con- 
nected by a spongy network of siliceous fibres. 9. Aulosplutera degantissima, Haeck. ; one 
of the Phaeodaria. Half of the spherical siliceous skeleton. (After Lankester.) 

the Thalassicollidae into either isosporous or heterosporous modes 
of reproduction ; and the Thalassophysidae fragment suddenly into 
hundreds of minute pieces (see pp. 137-8), without passing, so far as 
is known, into a sporulating phase. 

In the next division (Sphaerozoa) the polyzoic condition is 
characteristic of the nutritive phase. The colony or coenobium is 
spherical, elongate, or moniliform, though the individuals may 
retain the primitive homaxonic symmetry (Collosphaeridae) or 
become flattened (Sphaerozoidae). The skeleton may be absent, 
spicular, or spheroidal, and the scattered " nuclei " are homogeneous 
lumps of chromatin. 

The life-history of the Sphaerozoa is still incompletely known, 
though much has been done by Brandt (1885) to follow it. Accord- 
ing to this writer three kinds of sexual individuals or colonies 
occur : isosporous forms, heterosporous forms produced directly, 
and heterosporous forms produced after gemmation. In the Sphaero- 


zoidae both megaspores and microspores arise in the same individual j 
isospores in different individuals. Moreover, the asexual individuals 
are not all alike, but in certain genera at least some produce extra- 
capsular bodies (pp. 138-9), and those individuals which bud off these 
structures are, according to Brandt, young forms. These fertile 
young forms become in many cases heterosporous the extra- 
capsular body forming the megaspores, the intracapsulum giving 
rise to the microspores but in other cases the extracapsiilar bud 
develops into a new central capsule. Consequently we have two 
forms of heterosporous individuals and one isosporous form, and 
Brandt suggests that there is an alternation between the hetero- 
sporous and homosporous individuals. Famintzin, however, has 
reinvestigated the matter, and finds, in the vast numbers of full- 
grown colonies that occur in autumn at Naples, some are converted 
into isospores, some into heterospores, and many have extracapsular 
bodies. These last colonies divide into small winter ones, the 
majority of which possess extracapsular buds and develop into 
heterosporous forms. According to Famintzin there is no alter- 
nation of generations (13). 

Whilst the Sphaerozoidae thus either become heterosporous 
directly, or indirectly after division and the development of extra- 
capsular bodies, the Collosphaeridae have no extracapsular buds, 
and their mega- and microspores develop in separate individuals. 
The skeleton when present takes the form of a perforated shell, 
but notwithstanding these differences they are held to be rightly 
separated from the Sphaerellaria, with which Haeckel formerly 
united them. 

The Sphaerellaria include an immense number of solitary 
chambered forms, the majority of which are spherical, the remainder 
being elliptical or flattened. Eadial bars unite the chambers, but 
these bars are wholly ectoplasmic, and are never joined at the centre 
of the endoplasm as in certain Acantharia. The nucleus remains- 
single, but grows with the growth of the individual. 

The Acantharia form a primitive group of Eadiolaria with many 
interesting distinctive features. They retain homaxonic symmetry, 
but the pores of the central capsule are less closely set than in the 
Spumellaria. Through these pores there pass not only the cyto- 
plasmic bridges between ectoplasm and endoplasm, but also two- 
other radiating structures, namely, stiff pseudopodia (axopodia) and 
spicules. The latter meet in the centre of the capsule (Fig. 4 (7)), 
the former surround the centre and alternate with the spicules 
(Fig. 18), which pass outwards generally in five whorls. These 
emerge from the ectoplasmic surface at points through which five 
circles could be inscribed corresponding to the two tropical, two 
polar, and equatorial lines of the globe. 

The whole disposition strongly suggests that the radiating 



spicules have developed by a hardening of the stiff fibre of certain 
alternate axopodia which formerly met at the centre of the endo- 
plasm as in Heliozoa, to which group this order suggests other 
points of affinity. The peculiar nature of these spicules is the 
distinguishing feature of the order. They are composed, in the 
best investigated cases, of strontium sulphate (Biitschli, 1906), and 
not of a chitinoid organic acanthin-substance, as Haeckel supposed. 

Fio. 5. 

To illustrate the structure of the 
Nassellarian sub-family. A, Plagonis- 
cu,s tripodiscus, II., showing the central 
capsule (c.c) supported by the skeletal 
tripod. B, Cortina typus, H., showing 
the tripod and sagittal ring (5) enclos- 
ing the central capsule, within which 
are seen the podocone (p), the nucleus 
above, and three oil -globules. C, Tre- 
pospyris cortiniscvs, H., to show the 
formation of the helmet-like type of 
skeleton from the tripod and sagittal 
ring. (After Haeckel. ) 

The nucleus is a multiple structure, and the large body frequently 
mistaken for a nucleus (Fig. 4 (6, &)) is a Suctorian parasite. The 
Acantharia frequent the upper layers of the ocean (chiefly from 
the surface down to 300 metres), and are abundant in Arctic and 
Antarctic seas as well as in the intermediate zones. The yellow 
cells that in other Radiolaria are confined to the extracapsulum, 
occur almost exclusively within the central capsule in the 

The Monopylaria or Nassellaria include an immense range of 
forms. In the simplest the central capsule is supported by a 
siliceous tripod or tetrad spicule, often accompanied by a sagittal ring. 



It contains a peculiar cone of doubtful significance (Fig. 5, B, p). 
The ectoplasm streams out from the capsular pore-plate and forms a 
dense bubbly mass around this opening. From this point it passes 
as a thin layer around the capsule, so that the cytoplasm is asym- 
metrically distributed. These Radiolaria are, in fact, bilaterally 
symmetrical. Lateral outgrowths from the spicule or sagittal ring 
give rise to a helmet-like shell or "cephalis," in the upper part 

Eucyrtidium cranioides, Haeck., x 150; one of the Monopylaria. Entire animal a.s seen in 
the living condition. The central capsule is hidden by the beehive-shaped siliceous shell 
withinlwhich it is lodged. 

of which the central capsule is lodged. The cephalis becomes 
voluminous and often constricted, producing a vast array of specific, 
skeletal variety, the whole of which is produced by modification of 
a single spicule. The nucleus, though often lobed, remains single. 
Spore-formation is known to occur, but no form of reproduction has 
been adequately investigated. The bionomics of the group are 
quite unknown. 

The Tripylaria or Phaeodaria form another large group, most 



easily characterised by the brown, greenish-brown, or black accumu- 
lation of food material, debris, and resistant " phaeodellae " that lie 
in the oral half of its ectoplasm ; and they are also signalised by 
the mode of distribution of the capsular pores. In the majority of 
genera the endoplasm communicates with the ectoplasm only by 
a teat-like operculum and a pair of small lateral conical pores 
(the so-called astropyle and parapyles). In a few cases two 
astropyles occur, and in at least one genus (Atlanticella) only a 
single pore-plate is present. The skeleton varies greatly in structure 


S^ Pfi 

Fio. 7. 

Aulactiniuin actinastrum, H. ; a member of the Phapodaria. (After Haeckel, slightly 
modified.) A, astropyle ; C, calymma ; AT, double nucleus lying in the endoplasm ; P, 
parapyle ; PJi, phaeodium. 

and configuration. It is usually of a tubular nature, and the hollow 
cylinders are often subdivided by septa. The basis of these 
tubes, however, is formed by minute aciculate spicules which are 
surrounded by a gelatinous sheath, and between this sheath and 
the surrounding ectoplasmic matrix is a thin membrane, which first 
becomes silicified. This is followed by deposition of silica in the 
gelatinous sheath, and in this way complex spicules, often with 
candelabra-like appendages, are developed. A single or double per- 
forated shell may be present, the surface of which has a peculiar 
porcellanous appearance and " diatomaceous " structure. In the 


most complex Phaeodaria this shell acquires a bivalvular form and 
carries many peculiar processes (Fig. 32). 

The nucleus is a large, usually single structure, and undergoes 
a peculiar kind of mitosis accompanied by the formation of a great 
number of chromosomes. The development and nature of the 
spores is incompletely known. A characteristic feature of this 
order is the absence of the yellow cells that occur almost constantly 
in the other orders. This negative feature appears to be correlated 
with the presence of that remarkable and still imperfectly analysed 
complex, the phaeodium. The researches of Borgert (18) give 
some ground for thinking that the phaeodellae (see p. 119) are 
excreta, and if so, the retention of these substances in Radiolaria 
devoid of " yellow cells " lends support to the view, derived from 
a study of the Turbellaria (Keeble and Gamble [41]), that these 
symbiotic algae exert a depuratory function. 

Variation: Dimorphism. The Radiolaria present three kinds 
of structural modification. There is the divergent variation about 
one or more centres that constitutes a " species." There is racial 
somatic dimorphism in relation to pelagic or abyssal life. And 
there is gametic dimorphism both in early and adult stages of life 
in relation to reproduction. 

The conception of " species " in Radiolaria is only gradually 
assuming a form similar to that held in the case of other Protozoa. 
Hitherto skeletal characters have been mainly and rigidly employed 
for the erection of a vast number of specific forms. The larger 
collections made by Plankton expeditions of recent years have 
shown that many of these earlier species, and even genera, are 
either growth stages of one and the same form, fission products 
common to several species, or divergent variations referable to a 
central " type." The first kind of variation probably occurs in 
every Radiolarian and has been recently worked out for several 
Tripylaria (Immermann). In Aulokleptes flosculus, for example, 
spicules of three kinds can be met with, each one of which was the 
basis of a separate species in Haeckel's classification. It has been 
shown, however, by Immermann that the spicules pass through two 
or more forms before arriving at their definitive stage, and may be 
arrested at an intermediate stage. Further knowledge of the 
development of the skeleton will undoubtedly tend to diminish the 
profusion of species that Haeckel has proposed. But it is not 
skeletal characters only that are subject to change during growth. 
Among the Collodaria, in which the spicules are a subordinate feature 
and in some families entirely absent, the early stages of growth 
differ so greatly from the later ones as to render their identification 
a difficult matter and one particularly liable to misinterpretation. 
Thus the genus Adissa, which Haeckel brought forward as the 
most primitive of all Radiolaria, has been shown by Brandt (25) to 



be an early stage in species of the two families Thalassophysidae 
and Physematiidae. Even the presence of developmental stages is not 
decisive proof that the fertile protoplast or coenobium in question 
is a final stage in the life-history, since in certain forms 1 an early 
and variable reproductive stage is intercalated between the earliest 
phase and that of full growth. Fission introduces further com- 
plexities. The Acantharian genus Litholoplms was founded on 
stages of growth or fission products belonging to other genera ; and 
the division of the Collozoidae by fission leads to minute forms 
that might easily be mistaken for young stages, although they are 
reproductive individuals. We are thus led to the conclusion that 

Fio. 8. 

Racial dimorphism in Aulacantha scolymantha, x 26. (After Hacker.) A, deep-sea form ; B, 
pelagic form from Naples, 100 fathoms. C.c, central capsule ; Exo, ectoplasm ; Ph, phaeodium ; 
R, radial spicules ; Tf, tangential .spicules. 

a knowledge of the life-history is essential to the construction of a 
permanent classification, and that when this is obtained the species 
will be groups segregated about their several types. 

The dimorphism of Radiolaria is of two kinds : somatic and 
gametic. Somatic dimorphism is at present known only in few 
instances. It consists in the development of a small race of a 
widely ranging species in warmer surface water, and of a large race 
(usually three times the size of the former) in cold and deep water. 
Associated with these differences of size there is structural diversity. 
The spicules of the small race are fewer and simpler, the ectoplasm 
they support is delicate and limp, often sagging between the 

1 E.g. Collosphaera (Fig. 15, A). 



FIG. 9. 

Radial spicules of A, abyssal form of Auloscena 
vertitillatus ; B, pelagic form. (After Hacker.) 

siliceous appendages. The skeleton of the large race ends in more 
elaborate constructions, and stretches more tightly the tougher, 
thicker ectoplasm that covers the animal. Such racial dimorphism 

is known in Aulacantha scoly- 
mantha (Fig. 8), Circoporus sex- 
fuscinus, in Auloscena verticilla- 
tus, and probably will be found 
more commonly when looked 
for. Both races are capable 
of reproduction, and it is im- 
probable that they merge into 
one another, but it is not 
known whether the mode of 
reproduction is the same in 

Gametic dimorphism is 
more general and perhaps uni- 
versal, but is unaccompanied 
by any known diversity of 
somatic structure. It is there- 
fore comparable with the di- 
morphism of such Foraminifera 
as Discorbina and Truncatulina, 
and is signalised by the formation of isospores and of heterospores 
in distinct and differently constituted individuals. These processes 
involve the contents of the central capsule and are followed by the 
death of the ectoplasm. An individual Radiolarian is therefore only 
a phase in the life-cycle of its race, but the changes which lead up to 
the formation of isospores are so distinct from those that precede the 
development of heterospores, and involve such deep-seated nuclear 
transformations, that it is difficult to believe that similar individuals 
of any one generation can give rise to both forms of spore. On 
this ground Brandt has been led to formulate the view that 
isosporous and heterosporous individuals of any one species belong 
to alternate generations. Direct evidence of this alternation has not 
been obtained, and therefore the case of the Radiolaria is on a very 
different footing from the observed alternation in Foraminifera. 

Distribution : A, Vertical. The recently published reports of the 
German Plankton expeditions, though not yet complete, enable us 
to picture the vertical distribution of the Radiolaria more accur- 
ately than was formerly possible. The older records were derived 
from surface townettings and from Ehrenberg's researches on 
Radiolarian deposits at varying depths. They represented the 
group as occurring at all depths, even on the sea-bottom, and as 
increasing in variety with depth. The more recent exploring ex- 
peditions give a very different result. From them it appears that 


in Atlantic and Antarctic waters (1) the majority of Radiolaria 
occur not deeper than 400 metres ; that the Collodaria are em- 
phatically surface forms characteristic of the top stratum (0-50 m.) ; 
(2) that in the next stratum below this (50-400) the great develop- 
ment of Radiolarian, as also of diatomaceous, life occurs. Here the 
majority of Acantharia, many Spumellaria, and many Phaeodaria, 
e.g. Challengeridae, occur; (3) that in the still deeper water, 400- 
1000 metres, a still richer Phaeodarian fauna and a few Acantharia 
are met with, and that beyond this a few remarkable forms range 
down to 5000 metres. The vertical distribution of the Nassellaria 
is not yet adequately known, but it probably follows much the 
same lines as that of the Phaeodaria. 

B, Horizontal. The distribution of the class is extremely wide, 
as is readily understood from their dispersal by the great oceanic 
currents. Some forms are panplanktonic, e.g. Aulacantha ; some 
are bipolar: many are emphatically warm -water forms; others as 
characteristically follow cold currents. Such considerations enable 
us to understand the varying depths at which the same form may 
occur as its chosen current occupies now a deeper, now a more 
superficial position in the ocean. The greatest variety of species 
is met with in equatorial waters, and this fulness extends in 
diminishing variety north and south for some forty degrees. Then 
there follows, at least in the northerly direction, as in the case of 
many other pelagic orders, a barren zone, and finally Arctic waters 
show a Radiolarian fauna that is rich in individuals though poor in 
variety, and is apparently greatly inferior to that of Antarctic 
(Hacker). This mode of distribution explains the comparative 
poverty of the British Radiolarian fauna. Though the lack of 
research makes reserve necessary, it seems certain that these waters 
of the west and north-east coasts of Britain contain only a casual 
Thalassicolla and a few Acanthometrida, Sphaerellaria, and Phaeo- 
daria, outliers and stragglers of the rich Gulf Stream fauna. 
The great northern host passes by the Faroes and off the Hebrides, 
as the lists, pp. 144-151, show, and in those waters the researches 
of Murray, Fowler, and Wolfenden have revealed a number of 
interesting forms. 

The deposits formed by the accumulation of Radiolarian 
skeletons constitute a well-known element in the composition of 
littoral and deep-sea Globigerina ooze and of red clay. They make 
up certain of the clays, marls, and pumices found in the Miocene 
deposits of Barbadoes, the Nicobar Islands, and on both sides of the 
Mediterranean, as at Oran and Tripoli. Siliceous organic rocks 
of Palaeozoic and of Mesozoic age have been recently discovered in 
many parts of the world ; and microscopical investigations of these 
rocks have revealed an unsuspected wealth of Radiolaria in them. 
From the Cambrian age onwards, however, the families and even 


genera appear identical with those now living. Pre- Cambrian 
Kadiolaria are still doubtful (Hinde [44]). The Sphaerellaria (Poly- 
cystina) and Nassellaria are the chief contributors, since the 
strontium skeletons of the Acantharia are readily soluble, and 
therefore are unknown in recent deposits or in a fossil state, and 
the hollow siliceous spicules of the Phaeodaria also appear in- 
capable of resisting decomposition. Many skeletons formerly identi- 
fied as Radiolarian (such as Dictyota and Mesoscena) are now referred 
to the Flagellata or to other orders, but the Nassellaria Cyrtoidea 
form the majority, the Sphaerellaria, Discoidea, and Sphaeroidea 
the minority, of Jurassic Radiolaria in quartzites and coprolites. 
In later deposits of Miocene ages this predominance is maintained, 
but the species found are identical with or closely akin to living 

Central Capsule. The cytoplasm of Radiolaria is distinguished 
from that of other Protozoa by the great development, specialisa- 
tion, and delimitation of its ectoplasm. The boundary between 
this peripheral layer and the central nucleated plasma is almost 
always a distinct one ; and the few cases amongst the Acantharia 
and Sphaerozoa in which no limiting membrane can be traced, 
serve to show that this separation is the outcome of more primitive, 
undifferentiated conditions, which the Radiolaria display in early 
life, to which they revert during fission, and occasionally retain 
throughout life. 

The central capsule is the sign of this plasmic differentiation, 
and the mark of a Radiolarian. It consists of a single, or in 
Phaeodaria of a double, porous membrane of either chitinoid or 
mucinoid nature. Usually the capsule is of such tenuity as to be 
visible only after the use of reagents, or, as in Thalassicolla, it may 
be comparatively thick and areolated by the growth of ridges on 
its inner surface (Hertwig). 

The shape of the capsule is in general correlated with that of 
the configuration of the animal. In homaxonic Spumellaria and 
Acantharia it is spherical ; in lenticular and discoid forms it is 
ellipsoidal. In the bilateral Nassellaria it is elongate, and in the 
Phaeodaria spheroidal; but in the recently discovered spherical 
Thalassothamnidae it is lobate or branched (Fig. 10). The 
consistency of the central capsule, however, is not that usually 
associated with chitinoid structures. It is capable of extension, 
and in the concentric Sphaeroidea and Discoidea it is lobate and 
may enclose the inner shells one after another. In the helmet- 
shaped Nassellaria it throws out lobes through the basal plate of 
the shells. During the processes of fission and sporulation the 
central capsule in all Radiolaria becomes more or less completely 
dissolved to allow of the separation or escape of the endoplasmic 
contents. These phenomena show that the capsule is no per- 


manent excretion, but is composed of a substance capable of 
adaptation, by growth or dissolution, to changes in the endoplasm. 

The walls of this structure are perforated by fine pseudopodia 
that connect the endoplasm with the exterior in the manner 
severally characteristic of the Peripylaria, Monopylaria, and 
Tripylaria (pp. 102-9). 

The evenly distributed or segregated pores of the first group 
admit not only fine plasmic connections, but in Acantharia they 
also transmit axopodia and radial spicules. 

The single pore-plate of the Monopylaria, which, according to 


Fio. 10. 

Cytodadus spinosux. x 10. (After Schroder [38].) One of the Peripylaria, to show the 
branched central capsule (C.c), the radiate single spicule (Sp), and the voluminous ectoplasm 
supported by the spicular rays. It has been recently found off the coast of Japan. 

Hertwig, consists of perforated, thickened rods of capsular mem- 
brane, is not thoroughly understood. In most Nassellaria the 
pores are, of course, confined to one plate-like extremity of the 
.capsule, but they may be evenly distributed over the basal plate, 
confined to a peripheral zone, or to three circles, which in Tridictyopus 
project peripherally. Associated with this pore-plate is a peculiar, 
.cone-like, fibrillated structure which projects inwards towards the 
nucleus (Fig. 5, B, p). According to Hertwig this cone is an 
invagination of the capsular membrane, and the fibrillae are con- 
tinuations of those that pass through the pore-plate, on their way 
to join the endoplasm at the apex of the cone. Biitschli, however, 


is inclined to consider the cone as due to the coalescence of axopodia 
somewhat like those of the Acantharia (9, p. 439). 

The central capsule of the Phaeodaria possesses well-marked 
characteristics in its double nature and the presence and structure 
of its main opening or astropyle and of its two lateral parapyles. 
The former consists of a teat-like operculum apparently striated on 
the inner side owing to the septate character of the subjacent 
eridoplasm. The latter are made up of an inner bulb and an outer 
cone which opens on a prominence. The endoplasm under the 
bulb is also radially grouped, and in general it may be said, as 
evidence of the interchange of plasma through the capsular pores, 
that the endoplasm in their neighbourhood has a striated character. 

The morphological character of the central capsule is a moot 
point. Most authors, following Hertwig, hold it to be comparable 
to the shell-membrane of a Thecamoeba, which, however, Dreyer 
considers is covered by ectoplasm on both sides. It is possible, on 
the other hand, that the capsule is a basement membrane peculiar 
to the Radiolaria, and is a consequence of the differentiation of 
their cytoplasm in relation to pelagic life. Until its development 
is studied the question cannot be satisfactorily answered. 

Cytoplasm. The cytoplasm of Radiolaria, though one and con- 
tinuous, is separable anatomically and physiologically into intra- 
capsular and extracapsular portions. 

Flotation and dispersal, nutrition and stimulation are offices 
that devolve chiefly upon the ectoplasm ; storage and reproduction 
upon the endoplasm. During the early and nutritive stage of life 
the ectoplasm is predominantly active, during the reproductive 
phase the endoplasm is solely operative. Continuity of structure 
and community of function are expressed by an interchange of 
protoplasmic and metaplastic granules through and beyond the 
capsular wall. 

The ectoplasm consists of four chief layers from within out- 
wards : an assimilative zone of dense protoplasm around the 
capsule, a thick alveolar layer capable of secreting gelatinous and 
fluid spheres, an enveloping membrane guarding the animal from 
contact with its environment, and beyond this a fringe of radiating, 
contractile pseudopodia. This great development is primarily 
related to flotation. From Brandt's researches on the hydrostatic 
function of Radiolaria it is clear that the calymmal gelatinous 
spheres play the chief part of this office. These spheres he holds 
are viscous secretions of the ectoplasm and absorb water from 
without inwards. The specific gravity of the expressed fluid 
is, however, such as to point to water saturated with carbonic acid,, 
and as we pass from the inner to the outer zones of this alveolar 
layer, the spheres are found to become more and more vacuolar, 
until at the surface they are so tense as to collapse at a touch.. 


Brandt therefore considers that the outer pseudopodia upon con- 
tact with certain stimuli (wave-motion and heat) contract and 
transmit the stimulus to the subjacent alveolar protoplasm. This 
in turn contracts and the surface vacuoles collapse. When this 
process has been continued for a certain time the specific gravity of 
the animal is raised and a slow descent follows. Equilibrium 
is again established, the vacuoles are re-formed, and the animal rises 
again to the surface. 

The calymmal spheres do not, however, monopolise the hydro- 
static function. The flotation of Radiolaria is determined by 
extension of its surface as well as by the lowering of its specific 
gravity, and in this sustentative adaptation the outer pellicle 
and the skeleton play the chief role. The skeleton of the 
Acantharia is composed of a radiating series of tent-poles upon 
which the ectoplasm can be raised and tightened by the elastic 
filaments that pull up the baggy ectoplasm, which upon inflation 
by vacuolar water expands, and so raises the animal to a higher 
zone of water ; or again contracts, followed by deflation and sinking 
of the whole mechanism. 

Again, in Phaeodaria we have a still more elaborate skeleton, 
the appendicular parts of which are related to the formation and 
support of the ectoplastic membrane. In an impressive variety of 
sustentative adaptations the ectoplasm of Eadiolaria deposits silicic 
acid or strontium sulphate ; and the attempt now being made 
to trace a correlation between the variation of this support, 
the extent and thickness of the outer membrane, and the density 
and viscosity of various tracts of water inhabited by widely 
varying forms, has already met with some success (Hacker [35]). 
Racial forms occur. Aulacantha scolymantha, for example, only 
attains a diameter of 2 '3 mm. in warm surface waters; its ecto- 
plastic membrane is soft and its spicules small and simple ; whereas 
in deep, cold water (400-1000 metres) it reaches 7 mm. and 
consists of a much tougher envelope supported by more numerous 
spicules. Circoporus sexfuscinus and other Phaeodaria are also 
dimorphic and exhibit a similar differential relation to the surface 
and abyssal Avaters in which they occur. 

The ectoplasm rarely contains assimilates or other inclusions. 
Oil -globules, however, occur in the large Collodaria ; pigment 
(blue, black, brown, or red) in the Thalassicollidae, Sphaeroidea, 
Discoidea, and some Acantharia ; and concretions (probably 
proteid) in some Thalassicollidae. Yellow cells are generally 
present in the ectoplasm, and the only large division in which they 
are unknown is that of the Phaeodaria. In the Acantharia, 
however, they occur almost constantly in the endoplasm. A 
further account of these cells is given below. 

The myonemes are peculiar modifications of the basal ends of 



certain pseudopodia. They occur exclusively in the Acantharia 
Acanthometrida, and form circular groups of short, rod-like bodies 
clustered round each of the radial spicules (Fig. 11). Upon 
careful examination they are found to connect the ectoplasm with 
the pseudopodial covering of the spicule and to possess a high 
degree of contractility. Their form varies accordingly. When 
expanded the myonemes appear as homogeneous threads '006 to 
013 mm. long. When contracted they not only become shorter 
(012-'02) and thicker, but exhibit in many cases a very distinct 
cross-striping. They are, in fact, muscular structures comparable 



Fio. 11. 

Portion of a living specimen of Acanthometron pellucidum, one of the Acantharia, x900 
(after Schewiakoff), to show endoplasm and ectoplasm. The latter consists of vacuolated 
cytoplasm (E) slung up to the rod (S) by striated myonemes (.V), which are inserted into 
the sheath (Sh) around the rod. In the endoplasm two nuclei (N) and zooxanthellae (Z) are 

with the contractile fibrillae of Gregarines and Infusoria (Schewia- 
koff [33]), and they serve to raise or lower the hydrostatic, ecto- 
plasmic apparatus of these Radiolaria, and so to facilitate their 
ascent or descent. 

Another cytoplasmic modification of the Acantharia may here 
be mentioned, namely, the axopodia. They consist of contractile 
pseudopodia that radiate from near the centre of the endoplasm 
to the periphery of the animal, and possess an axial fibre around 
which an unceasing cyclosis of granules takes place. These 
axopodia differ from the ordinary pseudopodia of the Acantharia 
not only in their deeper origin but also in their more limited 


numbers and cyclical arrangement, and they resemble the peculiar 
pseudopodia of such Heliozoa as Acanthocystis in all points except 
in not arising from a centrosome. The peculiar cytoplasmic 
threads that compose the so-called flagellum of the Discoidea are 
also in all probability of a similar nature. This flagellum consists 
of immobile pseudopodia fused into a tapering mass which projects 
freely at one point of the ectoplasm, and its component pseudo- 
podia, unlike those of the surrounding calymma, can be traced 
almost to the centre of the endoplasm. They appear to spring 
from the nucleus. 

A peculiar accumulation occurs in the extracapsulum of the 
Tripylaria, to which the name phaeodium is given. It consists of a 
greenish or brownish mass concentrated about the main aperture of 
the central capsule, but extends around the capsule for a third of 
its extent. So constant and characteristic is this coloured mass 
that the term Phaeodaria is frequently used as an alternative to 

The constituents of the phaeodium in Aulacantha are various 
partly extrinsic, partly intrinsic. To the former class belong 
diatoms and the debris of other vegetal organisms, small Radiolaria, 
and Crustacea. Most of these undoubtedly represent food material ; 
the diatoms, however, may be symbiotic. The characteristic 
elements of the phaeodium are, however, the phaeodellae, which 
consist of spherical or ellipsoidal corpuscles which vary from less 
than 1 ju, to 20 /A in diameter. These corpuscles occur singly or in 
masses. They appear homogeneous, granular, or striated, and vary 
in colour from a hyaline transparency through yellow-brown, light 
and dark green, to black. They may be free from inclusions or' 
contain both blackish particles of varying size and refractive 
granular spheres and rods. Towards reagents they show great 
refractoriness, and do not give a uric acid reaction (Borgert). 

About the nature of these phaeodellae, opinion has long been 
divided. Haeckel maintained that they were symbiotic algae, 
other zoologists that they were food particles. The recent 
researches of Borgert on Aulacantha have suggested another 
explanation. Borgert has pointed out the resemblance of certain 
granules formed in the endoplasm in the neighbourhood of the 
astropyle to these phaeodellae, and he regards these corpuscles as 
excretory products of the endoplasm that pass out through the 
capsule and accumulate in the surrounding ectoplasm. Recent 
work on the brilliantly coloured algoid structures in bathybial 
Challengeridae and Concharidae have shown that probably both 
assimilation and excretion are carried on in the phaeodium (36). 

Endoplasm. The endoplasm is the site of storage and of 
reproductive changes. It consists of a granular streaming 
cytoplasm often highly vacuolated, and stratified radially and 


concentrically. Imbedded in it are fatty and proteid reserves, 
pigment, crystalline structures, and one or more nuclei. Oil- 
globules are generally present in the Spumellaria and Nassellaria, 
fatty granules in the Phaeodaria. The fat may be colourless or 
coloured red, yellow, brown, or blue. The pigment is often 
closely associated with the oil-globules, and occurs in Thalassophysa 
on the peripheral surface of the globules. The crystalline 


f ,Arm 

fti?3& <?l&fe X '^A 

t\*S>r.. .'':; ''**-jyLi& s 


Portion of a section through Planktonetla atlantica, Borg., one of the Phaeodaria, to show 
the phaeodium (Ph) tilling up the ectoplasm (Exo), x 80. (After Fowler.) Of. Fig. 29 for whole 
animal. The black horizontal line is the "diaphragm" or ectocapsular membrane, that is 
perforated by a single bundle of fibres (Fibr), if not also by the smaller similar structures (C). 
In the upper ectoplasmic half of the figure the complex phaeodium is seen together with 
branches (Sp) of the arms. In the lower half the delicate central capsule (C.c.) surrounds 
thejendoplasm (End) and nucleus (Nu), and is itself enclosed in a shell (Sh) that forms a float. 

structures are of two kinds : (a) small whetstone -shaped bodies 
probably of albuminous nature ; and (b) large rhombic structures 
indestructible at a red heat. The latter, regarded by Brandt as 
excretory, are in all probability crystals of strontium sulphate 
(Biitschli). With this exception the contents of the endoplasm 
may be regarded as reserve material destined partly for the 
metabolism of the animal itself, but more especially for the 
provisioning of the spores, into which the endoplasm breaks up. 
Nucleus. The nucleus of the Eadiolaria is still very im- 


perfectly investigated, and the following statement can only be 
regarded as a provisional account of its coarser features. The 
two chief phases of life are signalised by distinctive characters in 
the nucleoplasm. In the vegetative phase it consists of a single 
large vesicular structure, or of a few derived from this by mitotic 
division, or of many equivalent, amitotically produced, small nuclei. 
In only a few cases are chromidia or other nuclear derivatives as 
yet known to occur in this phase (Collosphaera, SiphonospJiaera, and 
Aulacantha), and there is no separation of somatic and germinal 
nucleoplasm. The Radiolaria are, in fact, homokaryota. Neverthe- 
less, at the advent of the sporulating phase, the nucleus displays 
new characters. Either it becomes differentiated and divides into 
spore nuclei ; or it fragments partly into chromidia and plasma, which 
recombine to form the spore nuclei, and partly into a residue which 
perishes with the parental exuviae. In this process we can detect 
a certain analogy with the extrusion of nucleoplasm during the 
formation of the spores in the Heliozoa. But since the fate of 
the Radiolarian spores is unknown, a just comparison of the two 
cases is at present impossible. 

The nucleus lies wholly in the endoplasm, and no chromidia or 
other nuclear products have yet been recognised in the extra- 
capsulum ; but the axopodia which radiate from the neighbourhood 
of the nucleus in certain Nassellaria, the similar fibrillae that run 
from the nucleus outwards to form the flagellum of the Discoidea, 
are indications of the paths along which the nucleus probably exerts 
its influence upon the ectoplasm, and vice versa. Further evidence 
of this perinuclear sphere of influence is found in the apparently 
porous character of the nuclear membrane (Physematium, Thalasso- 
lampe, and certain Sphaeroidea) and the radial arrangement of its 
peripheral plasma. 

The characters of the nucleus vaiy according as to whether it 
is a single or multiple structure. The Collodaria, Sphaeroidea, 
Nassellaria, and Phaeodaria are generally mononuclear : the Sphaero- 
zoa and Acantharia, polynuclear forms. In the first group the 
nucleus is vesicular and differentiated into membrane, sap, chromatin, 
and achromatin. In the second the nuclei are without a distinct 
membrane, and, in the vegetative stage, homogeneous ; their origin 
from the spore or zygote nucleus has been traced in no single 

One or two special forms of nucleus may be referred to. 
Among the Phaeodaria the majority possess a nucleus such as that 
shown in Fig. 15, A, together, in some cases (Aulacantha scolymantha), 
with chromatin particles scattered through the endoplasm. The 
Tuscaroridae, however, are peculiar in having (Figs. 13 and 30) 
an elongate nucleus, with a loop of chromatin enclosed by the 
nuclear sap. 



Among the recently discovered and reinvestigated Spumel- 
larian families, Thalassothamnidae and Orosphaeridae, a totally 
new type of nucleus has been found (Schroder and Hacker). It 

consists of a discoid structure 
('1 mm. diam.) enveloped by 
a crenate membrane, and is- 
composed of a thin cortical 
substance and a central mass- 
of very distinct nucleoplasm, 
the cortical and medullary 


substances being separated 
apparently by a membrane 
(Fig. 14). The central 
nucleoplasm contains segre- 

The central capsule and nucleus of Tuscarora , -, i i i , j 

nationalis. (After Borgert.) As, the astropyle; gated, ICCbly Chromatised 

Pa, the two parapylae ; Nu, the nucleus with its p- rnnn l P o imbedded in an 

chromatin band (Ch). x 45. &' a 

achromatic matrix ; the cor- 
tical layer, on the other hand, is densely chromatised. The 
most striking feature of this nucleus is perhaps the presence of 
lenticular bodies at intervals along the junction of its two com- 
ponent layers, or in one genus (Orosphaera) just outside it. These 
contain large compact lumps of chromatin imbedded in a less- 
densely staining medium. In addition to this central nucleus, 
scattered, chromatin-like granules (Fig. 1 4, s) occur in the endoplasm, 
and in Orosphaera these peripheral granules are unmistakable 
nuclei of a simple character. 

The shape and size of the nucleus often undergo considerable 
change during growth. It remains vesicular, large, and spherical,. 

FIG. 14. 

Portion of a section through the 
branched central capsule of Thalasso- 
thamnus. (After Hacker.) The centre 
of the capsule with its nucleus (N), endo- 
plasm, and inclusions are shown. The 
stratified concretions (s) stain with 
haematoxylin, arid are probably chro- 
midial structures. In Orosphaera (a 
genus which, according to Hacker, is 
closely allied to Thalassothamnus) these 
peripheral nucleoplasmic structures are 
capable of division. The nucleus (N) 
shows well the division into crenate 
membrane, peripheral chromatic layer, 
and the central, mainly achromatic sub- 
stance in which groups of staining 
gran tiles occur. Large lenticular bodies 
(/) of unknown significance occur also. 

and more or less chromatised in the Thalassicollidae and' 
Physematiidae ; but in the Thalassophysidae it becomes papillose, 
elongate, and serpentiform, its plasma not only differentiates into 1 
inner and outer substances, but the spherical or thread -like : 


chromatin accumulates at its periphery (Fig. 21, A, B). In the 
Sphaeroidea the nucleus becomes tubercular and follows the growth 
of the central capsule, as this encloses successive shells. In the 
simpler forms of Nassellaria the vesicular nucleus remains elliptical, 
but in the Cyrtoidea, in which it lies near the apex of the shell, it 
sends lobes (Fig. 4, 3) into the adjoining lappets. 

The multinucleate Radiolaria offer other distinctive characters. 
In the Sphaerozoa each individual of the colony possesses a gradu- 
ally increasing number of structureless, singly refracting nuclei, 
which multiply by direct fission, and have rather the appearance of 
nuclear fragments than of true nuclei. In the case of Collosphaera 
and Siphonosphaera, scattered chromidia (not associated as far as is 
known with reproduction) occur as well. In Acantharia the multiple 
nuclei have apparently a membrane and nucleoli, the multinucleate 
condition is constant, and the distinction drawn by Haeckel between 
such forms and oligo- or mononucleate Acantharia is a mistaken one 
due to the presence of a parasitic Amoebophrya (Acinetaria), which 
was mistaken for a nucleus (Part I. p. 423, Fig. 90). More difficult 
to account for is the careful description by Hertwig of a temporary 
nuclear condition discovered by him in a species of Acanthometron 
and of Amphilonche. In the comparatively few nuclei of young 
specimens, Hertwig found that the membrane became invaginated on 
its peripheral side, whilst the massive nucleolus showed differentia- 
tion into two parts. The neck of the infolded membrane became 
radiately arranged, and its deeper portion creased into circular 
folds lying one over another. After a time these appearances 
vanished and the nuclei resumed their simple spherical form. The 
phenomenon may be one of internal budding. 

The advent of sporulation is prefaced and accompanied by 
changes in the nucleus. These changes, however, are but imper- 
fectly known (p. 139). Vesicular nuclei shrink, their membrane gives 
way, and the altered chromatin and enclosed nucleoplasm either 
flows out into the endoplasm or gives rise to a nuclear figure and then 
disperses (see above, pp. 99-100, for Thalassicolla). From the frag- 
mented material spore-nuclei arise. By the former method isospore-, 
by the latter heterospore-, nuclei develop. In the Sphaerozoa, how- 
ever, the homogeneous scattered nuclei remain undifferentiated 
during the formation of isospores, and only exhibit a change from a 
singly to a doubly refractive property ; but previous to the develop- 
ment of heterospores their nuclei become modified into chromatic 
and achromatic portions, which are further differentiated in the 
mega- and microspores. 

In the Phaeodaria the ellipsoidal nucleus is usually a single 
large structure, but two or three nuclei may be present. It con- 
sists (Fig. 14) of a membrane containing a linin network. The 
chromatin is massed at the centre, and from this point radiating 


strands, threads, and lumps run outwards towards the periphery. 
In addition to these chromatised elements, threads and granules of 
another substance, the so-called paranuclein of Borgert (18), are 
present. Nucleoli are absent. 

The phenomena of nuclear division in this group have been 
carefully studied by Borgert (17, 18) and Karawiew (16) in 
Aulacantha scolymantha, but only mitotic division has been fully 
described. Direct division of the nucleus without elongation is 
known, but only a preliminary account has as yet been published. 
The behaviour of the nucleus during sporulation is unknown. 
Nuclear mitosis in Aulacantha exhibits five phases. In the first 
or spirem stage, the linin threads form a dense coil, along which 
the chromatin becomes arranged in a moniliform fashion ; a few 
remnants, together with the paranuclein, lie scattered through the 
nucleoplasm. The coil is in all probability never a continuous 
thread, and no distinct centrosomes appear at this or any subse- 
quent phase. The next stage consists of two events. The threads 
of chromatin become cut up into varying lengths, and split longi- 
tudinally so as to form rows of chromatin globules on either 
side of the linin threads. The second event is the condensation of 
these globules into thick short lengths of double chromosomes. 
The pairs so formed are unequal in size and different in form, 
some being spherical, some elongated or rod-like, but the members 
of a pair are alike. Amongst these the paranuclein granules lie in 
isolated heaps. The next or third stage is characterised by a 
second longitudinal splitting of the chromosomes in a plane at 
right angles to the first. The fission products separate, elongate, 
and become thinner and twisted, leading up to the fourth stage or 
second spirem phase, which is so far different from the first in that 
the chromatin elements are obviously discontinuous, and the nucleus 
as a whole has now become flattened, discoidal, and bent, in conse- 
quence of the loss of its membrane, so that it presents, in side 
view, a somewhat triangular outline, the apex directed towards the 
astropyle. The large mass of chromosomes is now organised on 
either side of a median transverse plane passing at right angles to 
the flattened nucleus. The position of this plane is occupied by a 
mass of short chromatin elements and debris, between which para- 
nuclein granules occur. The chromosomes are aggregated on each 
side of this central mass, which prevents them from being continuous 
from one side of the nucleus to the other, and are more densely 
crowded near the centre. The whole flattened structure stretches 
out until on the aboral side it touches the central capsule. The 
fifth phase is signalised by the appearance of the equatorial plate. 
The origin of this structure has not been described, but the 
chromosomes now arrange themselves in close relation to it, and 
become heaped up in parallel series, though still maintaining marked 



differences of length and thickness. The plate becomes twisted 
sigmoidally and divides parallel to its surface, the two columns 



Fio. 15. 

Mitosis in Aulacantha scolymantha. (After Borgert [18].) A, central capsule and resting 
nucleus showing distribution of chromatin. B, second spirem stage showing commencing 
separation of the chromatin. C, portion of sigmoidally curbed nucleus showing the equatorial 
plate, and the chromosomes definitely arranged about the middle line. D, separation of the 
two rows of chromosomes and of the two daughter plates into which the equatorial plate has 
divided. E, central capsule showing the withdrawal of the daughter plates and commencing 
reconstitution of the nuclei. A, B, and E x 150, C and D x 900. 

of chromosomes move apart and organise two daughter nuclei 
(Fig. 15). 



These complex mitotic phenomena offer many peculiarities, some 
of which are discussed by Borgert. The absence of a spindle and 
of centrosomes, the double splitting, great number and variety of 
the chromosomes, the peculiar twisting of the nucleus and equatorial 
plate, and the two spirem stages render this form of karyokinesis 
unique ; and in spite of the labour which has been bestowed upon 
its analysis, several points, such as the origin and fate of the equa- 
torial membrane and the formation of the daughter nuclei, are still 

Yellow Cells. Zooxanthellae occur commonly in the ectoplasm of 
Spumellaria and Nassellaria ; in the endoplasm of Acantharia ; and 


FIG. 16. 

land 2, two specimens of Collozoum inerme, showing zooxanthellae (Z) in the ectoplasm, xlOO. 
3, 4, and 5 are magnified views of a single xanthella, showing its escape as a biflagellated 
organism from the cyst which it forms during the palmella state ( x 330). K, the nucleus ; 
chr, the two chroma tophores ; the inclusions are hollow, amyloid grains. (After Brandt.) 

are absent from the Phaeodaria. Their occurrence is facultative 
and not absolutely constant. They are very abundant in orders 
with a well-developed calymma such as the Collodaria (both mono- 
zoic and polyzoic), less so in the Sphaerellaria, and in Physematiidae 
with no extracapsular vacuoles, and are absent in the Discoidea. 
Similarly, zooxanthellae increase in number with the increase of size 
of the animal or coenobium in which they occur. Young colonies of 
Collozoum up to 50 or 100 members contain few or no zooxanthellae, 
older ones become impregnated with them. 

The zooxanthellae of the Spumellaria are similar in structure 
and behaviour to those of Thalassicolla (pp. 97-8). They are usually 
spherical organisms with a single apparently homogeneous nucleus, 
capable of assimilating carbon and of forming sheaths of a singly 


refractive amyloid substance around a clear centre. In the Collodaria 
they vary from '015 to '025 mm. in diameter ; in the Sphaerellaria 
from '005 to '01 mm. In the Nassellaria the zooxanthellae are 
very small in some Cyrtoidea (Eucecryphalus) ; very large in others 
(Eucyrtidium, Dictyopodium). A cellulose wall is present and en- 
closes cytoplasm which contains two chromatophores impregnated 
by chlorophyll and diatomin. In addition to the scattered hollow 
vesicular, singly refractive structures that react to iodine by a 
violet or bluish-violet tint, other doubly refractory granules occur, 
and these are unaffected by iodine. After the death of the ecto- 
plasm in which these zooxanthellae live, they pass into a palmella 
stage and issue as biflagellated organisms upon a free stage. The 
structure and life-history of these zooxanthellae prove that they 
are organisms living in association with Eadiolaria, but it is not 
possible to assign them to their true systematic position. Most 
authors, following Biitschli, have placed them in the Crypto- 
monadinae, a small heterogeneous group of simple algae ; but, as 
Schaudinn has pointed out in his work on the zooxanthellae of 
Trichosphaerium (42), it is also possible that these organisms have 
quite other affinities. Brandt (10a) and Klebs (46) have drawn 
attention to the similarity between the flagellated stage of the 
xanthellae and the Peridinian Exuviaella marina. Further investiga- 
tion of the behaviour of these yellow cells is necessary before their 
position can be accurately denned. 

Yellow Cells of Acantkaria. The xanthellae of the Acantharia 
differ in many ways from those of other Radiolaria. They are 
mainly intracapsular, and always naked cells. In some families 
they assume a spherical form, in others an irregular amoeboid shape. 
These cells pass by easy transitions to mere heaps of pigment 
granules. When numerous they vary in size from '006 to '008 
mm. When few they attain a much larger size, '015 to '03 mm. 
The latter, which are found in Acanthoniidae, Lithopteridae, and 
Amphilonchidae, are probably the largest zooxanthellae known. In 
Acanthonia tetracopa and other members of the same family, besides 
the usual intracapsular mass of zooxanthellae, a few occur now and 
then in the extracapsulum. In Dorataspis and Actinomma large 
amoeboid zooxanthellae occur regularly in this position. These 
structures are almost constant in Acantharia, but they are absent 
in young specimens and in the few species taken in deep water. 

The observations of Brandt (lOrt) on the finer structure of the 
Acantharian zooxanthellae suggest that they have acquired a much 
closer association with these Radiolaria than have those of Spumellaria 
with their host, and that the older view of their nature was nearer to 
the true significance of the association than the modern one that 
regards the zooxanthellae as merely immigrant algae. Haeckel and 
Hertwig regarded them as pigment cells formed by the segregation 



of the scattered granules and vesicles about so many nucleated centres- 
in the endoplasm, and therefore as integral parts of the Radiolarian, 
acting the part of storing reserve material. Brandt has shown that 
their structure, though not suggesting this view of their origin, serves 
to explain the connection between the pigment granules, pigmented 
granular heaps, and definite yellow cells. Starting from the last, 
with its single nucleus, plates of diatomin, numerous amyloid vesicles 
and refractive granules, Brandt finds other xanthellae with multiple 
minute nuclei, and by fragmentation of these yellow cells he accounts 
for the presence of the isolated yellow granules, each of which, he 
affirms, is a living corpuscle and possesses a very small nucleus 
(lOa, p. 237). This degeneration of the zooxanthellar nucleus into a 
heap of chromatin granules, associated with the breaking up of the 


Fid. 17. 

A-C, yellow cells (zooxanthellae) of Acantharia. (After Brandt.) A, large amoeboid cell 
from Acanthonia tetracopa. B, C, spindle-shaped zooxanthellae (A. tetracopa). D, single xan- 
thella of Thalassophysa sanguinolenta, to show its cell-wall (C.w), hollow, singly refractive 
inclusions that stain bluish violet with iodine. G, doubly refractive granules unaffected by 
iodine, x 1000. . 

cell, is probably not to be explained through digestion of the yellow 
cells by the Acantharian, but as a consequence of the intimate 
association between the two structures. Unlike the zooxanthellae of 
the Spumellaria, which live, divide, and sporulate after the death 
and dissemination of their host, those of the Acantharia lose their 
power of independent existence, and when the endoplasm in which 
they occur becomes transformed into isospores or heterospores they 
too pass into these spores in the form of granules and starch 
grains. Thus the flagellated heterospores of Xipliacantha alata 
(Fig. 26, A) contain a mass of yellow granules, besides an amyloid 
body (staining blue with iodine), which is constantly present in the 
iso- and heterospores of this species. It is therefore possible that 
the yellow cells of Acantharia pass from mother to offspring, and it is 
certain that amyloid deposits are so transmitted. The zooxanthellae 
of Acantharia, therefore, once they have entered the Radiolarian, 


never leave it. They become assimilating granules, apparently 
incapable of independent life, and are transmitted from parent to 
offspring. In the former conclusion we have a remarkable parallel 
to the history of the green cells (zoochlorellae) in Convoluta roscoffensis 
(Keeble and Gamble [41]). 

The nature of these interesting zooxanthellae is not satisfactorily 
settled, but the scanty evidence points to affinities quite distinct 
from those of the other Radiolaria. In the absence of a knowledge 
of the life-history, Brandt's view is as likely as any other, but it is 
by no means certain that all the Acantharian zooxanthellae are 
of similar parentage. This view is that the zooxanthellae of 
Acanthoniidae and Dorataspidae are isolated spindles of Labyrinthula 
vitellina or of some allied species, and Brandt (10a, p. 239) points 
out the agreement between the two structures in their shape, size, 
colouring, and nuclei. 

The association between Eadiolaria and the zooxanthellae is 
usually regarded as a symbiosis, i.e. one of mutual advantage. It 
is, however, clear from the foregoing description that no single 
formula will cover the important facts (1) that we have degrees of 
intimacy that have grown up between the two organisms; and (2) 
that the last term in the series of association is one to which 
symbiosis in any but the widest sense of that term is inapplicable. 

The origin of the association is probably to be traced to the 
hunger for nitrogen on the part of the zooxanthellae ; to the 
minimal quantity of inorganic nitrogenous food-stuffs in the warmer 
seas (Johnstone [45]) ; and to the convergent adaptation of 
Radiolaria and zooxanthellae to life at or near the surface of the 
ocean. This pelagic and insolated station is attained by the 
Radiolaria through the evolution of calymmal structures in which 
nitrogen is in all probability abundantly present. These swarms 
of inert mucilaginous Radiolarian capsules and colonies are therefore 
in every way suitable media for the nutrition of the zooxanthellae. 
Attracted in all probability chemotactically by the nitrogenous 
stores in the mucilage, the zooxanthellae enter the ectoplasm and 
then divide and assimilate. Protected by their cellulose envelope, 
they can at first resist the digestive enzymes of their host; 
ultimately, however, their nucleus becomes degenerate, and with 
this change the protective wall, whose formation it governs, becomes 
weakened. In this way some of the daughter-cells of the primary 
zooxanthellae become food for their host (Famintzin). The 
Radiolarian, which in its early stages fed on Peridinians, Infusoria, 
and small Crustacea, ceases to ingest solid food and relies upon the 
reserves it has accumulated or upon the secondary xanthellae for 
its supplies. Meanwhile, its nitrogenous metabolism, and possibly 
its intramolecular respiration, is maintained by the xanthellae, 
which are removing the waste nitrogenous substances. In confirma- 



tion of this statement reference may be made to the Phaeodaria. 
This group of Radiolaria possesses no zooxanthellae, and might 
therefore be expected to show some accumulation of excretory 
granules. This appears to be the case, for the complex phaeodium 
is made up of refractory, insoluble vesicles which are generally 
held to be excretory substances. The association of diatoms with 
Radiolaria has probably a similar significance. 

Finally, when the endoplasm sporulates the dying ectoplasm 
serves as a medium in which the zooxanthellae rapidly divide and 
issue as naked biflagellated spores upon a new, free existence. In 
the case of the Acantharia, which are also mainly epiplanktonic 
or surface organisms, the zooxanthellae are naked cells, almost 
exclusively confined to the central portion of the Radiolarian. 
Whether they develop from antecedent zooxanthellae that occur 
in the spores of Acantharia or infect it from sea-water, or whether 
both modes of origin obtain, is at present unknown. The apparent 
absence of xanthellae from young Acantharia makes the first sugges- 
tion unlikely. Within the central capsule they divide, multiply, 
and assimilate. Certain of them fragment into particles, the 
process being initiated by nuclear fragmentation, so that the 
zooxanthellae are no longer cells but mere chromatised, pigmented 
corpuscles, associated with free granules of starch or amyloid 
substances. There is no evidence to show whether in this or in 
the earlier coherent stage the xanthellae are digested by the 
Acantharian. They become in the last event mere assimilative 
corpuscles, and when the endoplasm sporulates the whole of the 
zooxanthellae, with their associated starch, pass into the bodies of 
the flagellated spores, and are probably used up as food by the 
developing zygote. Throughout this series we see that, in opposi- 
tion to the idea of mutual benefit, the animal is the predominant 
partner. The association is one beginning with myxophytism and 
leading to a case of parasitism, in which the zooxanthellae are the 
host and the Radiolarian the parasite. 

Skeleton. The skeleton of the Radiolaria has developed in each 
of the great sub-classes into a complexity of form and variety of 
detail that are found in no other group of animals. So characteristic 
are the skeletal products that it is usually possible from them alone 
to recognise broadly the systematic position of the organism that 
produced them. So complex and diverse a tracery seems utterly 
beyond the needs of simple Protozoa living under apparently similar 
conditions of pelagic life ; and though attempts have been made to 
explain this manifold skeletal development in terms of cytoplasmic 
structure, its variety still evades a biological treatment. Recent 
investigation has, however, done something to reduce this variety 
to a few plans, and to attach a biological meaning to some of its 
elaborations. These results justify the hope that, as we come to 


regard the skeleton as a response to the varying media, stresses, 
and strains that fall upon the cytoplasm from within and from 
without, that then its utilitarian character Avill be more completely 
recognised, and its variety found to be explicable in terms of com- 
position, mode of deposition, and the need of response to widely 
varying combinations of stimuli that occur in the apparently mono- 
tonous sea. Two very different substances compose the greater 
part, and probably the whole, of these skeletal structures. In the 
Spumellaria and Nassellaria pure silica is present ; in the Phaeodaria 
the silex is mixed with organic substance ; but in the Acantharia 
a substance is present which, from the time when it was first 
described by Johannes Miiller to the present, has given rise to 
differences of interpretation. Miiller, relying on the indestructible 
nature of the Acantharian skeleton when heated, regarded it as 
siliceous. Haeckel found that it was apparently destroyed by heat, 
and regarded it in the main as an organic horny substance which 
he called acanthin. Schewiakoff (33) tested its properties and 
attempted a quantitative analysis, the result of which went to show 
that the so-called acanthin was a complex silicate. Quite recently 
Biitschli (39) has rein vesti gated the skeleton of Antarctic and of 
fiome Mediterranean Acantharia, and has proved that in these 
cases it is composed of strontium sulphate. 

The diverse forms of Radiolarian skeletons are largely founded 
upon developments of scattered aciculate and tetrahedral spicules. 
Dreyer has indeed attempted to trace the evolution of the skeleton 
(1) in the Acantharia to an axopodial type derived from the 
hardening of the axis that runs down the peculiar radiating 
pseudopodia of this sub-class ; and (2) in other Radiolaria to the 
modifications of a tetrad spicule, which in turn he traces to the 
deposition of silica at the intersecting planes of adjacent cyto- 
plasmic vacuoles or alveoles ; but the absence of a knowledge of 
the development of the skeleton rendered this attempt suggestive 
rather than convincing, and there are many forms of skeleton 
which it is difficult to assign to any conceivable modification of the 
tetrahedral type. In the present state of our knowledge it must 
be admitted that the vacuolated cytoplasm has the power of 
depositing its silica in the form of perforate or imperforate shells, 
plates, and processes, so that in addition to the spicules there is 
often a great development of siliceous matter, the form of which 
cannot be referred to the alveolar structure of protoplasm. 

In form as in composition the skeleton of the Acantharia is 
sharply marked off from that of other Radiolaria. With few 
exceptions, it consists of twenty rods united in various ways : (1) by 
opposition and also by adcentral processes ; (2) by fusion of all or 
of opposite pairs, at the centre of the endoplasm. These radii are 
.disposed so as to emerge from the spherical cytoplasm along five 



circles, which may be compared to the equatorial, the two circum- 
polar, and the two tropical circles of the globe (Muller's law). In 
a few cases two radii mark the vertical axis, and the other eighteen 
are disposed in three circles an equatorial one, and the other two 
respectively 45 above and below it (Brandt's law) ; whilst in the 
apparently primitive Astrolophidae the spines vary in number and 

; AX. 

Fio. 18. 

Acanthonia tetracopa in its two extreme phases of expansion and contraction, one half of the- 
animal being drawn in each case. The relation of the myonemes to the ectoplasm, and their 
insertion into sheaths around the radial spines, is also seen (cf. Fig. 11). The full number (20) 
of spines is not indicated. (After Schewiakoff.) x 170. 

possess no regular arrangement beyond their radial disposition. 
This loose order is repeated in the early development of the Acan- 
thoniidae. The young of this family possess ten loose rods arranged 
crosswise, which subsequently become divided at the centre of 
the capsule into the typical twenty radii. In the Acanthochias- 
midae the distal portion of each radius gives off tangential processes- 
which unite with those of adjoining spines and so form a perforated 


shell. By repetition of the process farther along the radii a second 
and succeeding concentric shell may arise, In the most modified 
case (Sphaerocapsidae) the lattice alone is present, but the place of 
the radii is shown by twenty large pores distributed according to 
Muller's law. 

In the Spumellaria the skeleton is either absent, spicular, or 
shelly. Both spicules and perforated shells are often present 
simultaneously, and have evidently developed independently in 
two of the main subdivisions Sphaerozoa and Sphaerellaria. 
But whilst in the former the shell is single, in the latter it often 
becomes multiple, interconnected by radial bars, and flowers out 
into a wealth of appendicular growths that characterise this vast 
group, which numbers two-fifths of the known Kadiolaria. The 
Sphaeroidea retain the homaxonial form ; the Discoidea have only 
the first or first and second chambers spherical, and farther outwards 
become flattened and often cruciform, the arms of the cross being 
frequently divided into a large number of chambers, into all of which 
the endoplasm and its associated pigmented oil-globules may pass. 
Other modifications are mentioned in the conspectus (pp. 144-145). 
In the Nassellaria, the Kadiolarian skeleton develops into its richest 
expression of geometric form. Its simplest types consist of a single 
or multiple ring and of a tripod or tetrad (see Fig. 5), and from 
these a helmet-shaped perforated shell has arisen, apparently by 
lateral extensions of the simpler plan. Such a cephalis may be 
simple or divided both sagittally and transversely by one or more 
constrictions, and in exceptional cases a spherical shell may be 
developed. The most interesting feature of this group is that the 
whole of its variety can be traced fairly confidently to the modifi- 
cations of a single element which Biitsclili (8) believes to be a 
ring and Dreyer (15) a tetrad spicule. 

The skeleton of the Phaeodaria has followed another line of 
evolution. It consists essentially of minute aciculate spicules 
imbedded in a gelatinous matrix. Between these a jelly-like 
substance is secreted ; the inner layer of this matrix becomes silici- 
fied to form a tube, the cavity of which is often subdivided by one 
or more septa ; or the intermediate jelly may also become silicified 
as a porous plate or shell of porcellanous texture. Commencing 
with the Phaeocystina, in which the skeleton is absent or composed 
merely of isolated radial and tangential spicules, the formation of a 
lattice-shell has come about in several ways. The simplest mode is 
that seen in the Aulosphaeridae, in which the tangential spicules 
unite to form an open peripheral network. To this a second shell 
may be added by the formation of a reticulum immediately outside 
the central capsule (Cannosphaeridae). If the outer shell is absent, 
a condition found in the Castanellidae is obtained. In these 
Phaeodaria the single shell is composed of two conjoined membranes 


imbedded in a porcellanous impregnation throughout which minute 
aciculate spicules occur. It is provided with an oral opening on the 
end of a projecting and often spiny peristome. Again, this inner shell 
may assume a bi valvular form (Fig. 32), and then carries a number 
of complex appendages. Some of these are branching hollow 
species, terminating in anchor-like expansions ; others constitute the 
"galea" and "rhizocanna" (see Fig. 32, p. 151). 

Biological Significance of the Skeleton. The results of recent 
investigation point to the conclusion that the chief skeletal function 
is a hydrostatic one and is effected by stretching or folding the 
superficial ectoplasm. The older conception of the skeleton as 
projecting freely beyond the cytoplasm has been shown to be a 
mistaken one in many instances, and it is probable that the skeleton 
is during life covered by the outermost delicate plasmic layer 
in all Radiolaria. Between the characters of this layer and the 
development of the supporting rods a definite relation holds for 
certain forms. A few widely varying Radiolaria are dimorphic, a 
small pelagic variety and a larger abyssal form being readily and 
apparently rightly distinguishable (Aulacantha scolymantha, Auloscena 
and Sagosphaera-species). In these cases the surface-form possesses 
a delicate ectoplasmic layer, and the supporting rods are simpler 
and shorter, whereas in the bathybial variety the outermost 
cytoplasm is dense, more voluminous, and usually more stiffly sup- 
ported by verticillate skeletal projections. The graceful and 
elaborate skeletal appendages of other Phaeodaria are probably to 
be explained not as a means of catching food, but as a support for 
the ectoplasm ; and the whole plan and construction of the tubular 
skeleton in these forms is no doubt related intimately to the 
pressures that fall upon this limiting layer. 

In connection with this sustentative function of the Phaeodarian 
skeleton, the mode of formation of its tubular systems offers some 
features of special interest. The most general mode is that indi- 
cated at the close of the last section (p. 133), and in this method 
minute needle-like spicules form the centre around which tubular 
developments of silica take place. But in addition to this intrinsic 
centre, many Phaeodaria have adopted extrinsic objects, and around 
these as catalysators, the tubular silica is deposited. Like other 
Radiolaria, but to a greater extent, the Phaeodaria ingest quantities 
of foreign bodies, with which their phaeodium is distended. Amongst 
these ingesta, diatoms and Radiolarian skeletons are abundant. 
From Phaeodaria, in which such gatherings are casual, we can trace 
a series leading to forms in which diatom-selection becomes a regular 
habit, associated directly with the formation of a radial skeleton. 
Thus Aulographis pandora and Auloceros arborescens from the Atlantic 
and Indian Oceans contain in their phaeodia frustules of lihizosolenia, 
and spicules of many species of Aulacanthids picked up apparently in 



a casual manner, and probably serving to increase the extent of 
exposed surface. Cannosphaera from Antarctic seas .possesses a 
hollow skeleton the tubes of which are almost filled with masses of 
the diatom Corethron ; and finally, in Aulokleptes (Fig 19) and 
Aulodendron the diatoms are planted radially in the ectoplasm, 
surrounded by a mucilage, and 
finally incorpoi'ated into the walls 
of a hollow radial tube, the lamellae 
of which are laid down from within 
outwards, and the top of which is 
moulded into the form severally 
characteristic of the species (Immer- 
mann, Hacker). 

The biological significance of 
the varieties of Nassellarian spicule 
and of the scattered Spumellarian 
spicules and lattice - shells is at 
present quite obscure, but the 
skeleton of the Acantharia offers 
perhaps the clearest case of func- 
tional significance to be found in 
the whole group (Dreyer, Brandt, 
Popowsky). The twenty radial 
spokes of the Acanthometrea serve 
as so many tent-poles for the in- 
sertion of the myonemes (Figs. 11 
.and 18) that hoist the calymmal 
cones. This action, combined with absorption of water into the 
vacuoles, causes a swelling of the cytoplasm and brings the 
animal towards the surface ; whereas relaxation of the myonemes 
and contraction of the calymma depresses it beyond the reach of 
wave-action. The skeleton of this subdivision is, however, related 
to hydrostatic ends in another way. The definite arrangement of 
the twenty spines according to what is known as Miiller's law 
(p. 132) has recently been correlated with flotation and dispersal. 
Brandt has shown that the distribution of the radii in five alternate 
and superposed circles, each of four spicules, is such as to expose 
them freely and without overlapping to the viscosity and resistance 
of the water. The absence of vertical or axial spines is also intel- 
ligible, since they would increase the weight of the body without 
giving additional buoyancy. Moreover, the shape as well as the 
arrangement of the spines assist the Acantharia in their flotation 
and dispersal. Like all other Radiolaria, these are dependent on 
currents and drift for their dissemination. In order to utilise this 
horizontal force, the radial spokes are frequently provided with four 
flanges or blades, which serve the double purpose of encountering 

Fio. 10. 

Spicule from Aulokleptes floscvlus formed 
around a dividing diatom Rhizosoknia. 
(After Immermann.) x 55. 


sustentative and propulsive forces. When these blades are wanting 
and the spines are merely flattened, they are set in each of the 
three circles, so as to turn the flat edge somewhat differently to the 
water, the equatorial ones lying flat on the water, the tropical ones 
turned half over, and the polar spines set on edge. By this means 
the amount of resistance to the water in every direction is increased. 
The exceptionally wide distribution of the Acanthometrida is some 
confirmation of these deductions. 

Fission Reproduction. The phenomena of multiplication and of 
reproduction are still imperfectly known. Binary or multiple 
fission occurs in some Spumellaria, Acanthometrida, and Phaeodaria. 
Gemmation is a rarer mode. It produces the extracapsular bodies 
of the Spliaerozoidae, and is found in one species of the Acantharia 
and of the Phaeodaria respectively. The development of zoospores 
is a general phenomenon, but has been followed in detail only in a 
few cases. Plastogamy is unknown. 

The mode of increase by fission is probably restricted to those 
Radiolaria which have no spicules or a lax and osculate skeleton. 
Binary fission occurs in the Thalassicollidae, some Acanthometridae, 
and in two families of Phaeodaria. Division both of the Sphaero- 
zoid colony and of its component individuals takes place at intervals. 
Multiple fission occurs in the Thalassophysidae. The process is 
usually initiated by changes in the endoplasm and nucleus, and a 
long interval may follow before any corresponding alterations occur 
in the ectoplasm (Phaeodaria). 

In the Acanthometrida (Acanthoniidae) binary, quatenary, 
and multiple fission are said to occur (Popowsky). The former 
process is illustrated in Fig. 20. The skeletal rods separate at 
their central ends into two bundles, the nuclei segregate into two 
groups, the central capsule divides, and ultimately fission takes 
place. The fission - products are, however, asymmetrical, and 
Fig. 20 shows how the new radii are developed and how the rods 
are swung into position, probably by contraction of the myonemes 
inserted into them, until the whole arrangement is brought into 
conformity with Muller's law. 

Fission in the Phaeodaria is carried out in several ways. 
Aulacantha scolymantha is the best-known example of the direct 
process. In this Radiolarian the large single nucleus divides either 
by mitosis or amitotically ; the endoplasm segregates round the 
daughter nuclei ; the central capsule, after disappearing for a time, 
re-forms about the two masses. Lastly, the phaeodial complex, the 
calymma and spicular skeleton are subdivided each into two groups, 
and the whole organism divides into two. In the Phaeodaria, 
which possess a shell, one or more modifications of the process are 
found. The helmet-shaped Challengeridae, for example, undergo 
fission within the shell. One half of the organism now escapes 



through the oral aperture and develops into a new individual 
{Borgert [2 la], p. 100). 

The most remarkable case of multiple fission occurs in the 
Thalassophysidae, and constitutes the only known means of increase 

FIG. 20. 

Illustrating fission in the Acanthometrida. (After Popowsky.) A, Acanthometrnn bifidum 
about to divide. The spicules are arranged in two bundles. The central capsule has dis- 
.appeared. The ectoplasm is a mere hyaline border round the granular endoplasm, x!50. 
1$, lission of Amphilonche atlantica. My, the myonemes, xloO. C, regeneration of the same ; 
formation of a directive large spicule, x 150. D, spicules reassuming their characteristic 
arrangement, x 150. 

in this family. Fig. 21 illustrates the process, which has been 
investigated by Brandt (25). The central capsule and nucleus 
become irregular-branching, vermicular, or radiating structures. 
The oil-globules and their associated pigment granules become dis- 
seminated through the endoplasm. Then the nucleoplasm breaks 
tip into a vast number of minute homogeneous corpuscles, followed 



by rapid division of the capsule and endoplasm. The ectoplasm 
fragments and the products are disseminated through the water. 
Each minute product consists of several nuclei lying in a pigmented, 
oily fragment of endoplasm and supported by a portion of the 
original ectoplasm. The further history of these bodies is unfortu- 
nately not known. 


FIG. 21. 

Multiple fission in Thalassophysidae. (After Brandt.) A, central capsule and nucleus of 
Th. spiculosa, x 40. B, section of the nucleus to show the two zones of nucleoplasm and the 
vermicular nucleoli in the outer layer, x 66. C, Th. pelagiea about to divide ; the nucleus has 
undergone fragmentation. D, multiple fission of the central capsule of Th. pelagica. E, 
enlarged view of a portion of the same, x 200. F, stained portion of capsule of the same ta 
show nuclei before fragmentation of the capsule. G, division of central capsule of Th. sanguino- 
lenta, x 7. C.e, central capsule ; N, nucleus of vegetative individual ; NI, nucleus of frag- 
menting individual ; On, In, outer and inner zones of endoplasm. 

The separation of a portion of the Radiolarian organism as a- 
bud is a rare phenomenon, of which the " extracapsular bodies " of 
the Sphaerozoidae offer the best example. These structures occur 
in small colonies of Cullozoum inerme, C. radiosum, C. fulmim, and of 
Sphaerozoum neapolitanum. They consist of a lobate, highly refrac- 
tive, cytoplasmic mass, containing a group of modified nuclei 
ranged about a grape-shaped mass of fat, and are loosely attached 
to the colonial jelly (Fig. 22). These extracapsular bodies are 
budded off from the endoplasm of certain members of the colony in 
which they occur, and are at first uninuclear. According to Brandt's- 



account (10) these bodies have a twofold significance. Either 
they become additional members of the parental colony and develop 
central capsules, or they become megaspores and the small parental 
endoplasm develops microspores. In his later work Brandt lays 
additional stress on the latter fate. He has not only seen the bean- 
shaped active megaspores formed by the extracapsular bodies, but 
(26, p. 264) also the mass of microspores formed by the small 
capsules which had budded off these bodies : a proterogynous 
arrangement. It should be added that Brandt affirms very strongly 
the juvenile nature of these small budding colonies ; whilst Famintzin, 

FIG. 22. 

Collozoum sp. Portion of a colony showing extracapsular bodies (E.C). 
x 100. (After Brandt.) 

working in the same locality, asserts that their small size is due to 
fission of full-grown coenobia (13). 

Spore - Formation. Flagellated spores occur in the four main 
divisions of the Radiolaria, but their exact nature is only known in 
some Collodaria and some Acantharia, and it is in the former order 
that their formation has been traced. The process is described for 
Thalassicotta on pp. 99-102. 

Isospores. The development of isospores in the Sphaerozoa 
takes place in colonies distinct from those that produce heterospores. 
After a vegetative life of several months these colonies exhibit 
characteristic changes (Fig. 25). The nuclei become ranged in a 
single or double row just beneath the capsular membrane. Without 
becoming obviously differentiated, these lumps of chromatin divide 
directly and acquire a doubly refractive character. Hundreds of 



minute crystals arise in the endoplasm, a few larger ones also in certain 
Collosphaeridae. The single oil-globule of each capsule becomes 
very rapidly subdivided into as many minute vesicles as there are 
nuclei, and in association with this process a blue pigment develops 


FIG. 23. 

Collosphaera huxleyi. Optical sections of different growth-stages to illustrate (A, B) dimor- 
phism (Si, S'>) in early and later stages, and (C, D) the formation of isospores. A, young actively 
dividing colony (the young reproductive phase of Brandt, comparable with the. formation of 
extracapsular bodies in Sphaerozoidae). Many individuals are naked central capsules with 
one or more nuclei ; others have a shell (.S']) and are larger and already provided with 
zooxanthellae (z). B, later vegetative phase. The naked capsules have now secreted a large 
shell (.S 2 ), and a marked dimorphism has resulted. C, part of a full-grown colony about to 
sporulate. The formation of isospores is indicated by the grouping of the nuclei. D, later 
stage in isospore-formation showing the crystals aggregated about the oil-globule. x 75. 
(After Brandt.) 

in Myxosphaera coerulea and Collosphaera huxleyi. Numerous vacuoles 
arise in the centre of the capsule, each with a central granule, until 
a number equivalent to that of the nuclei has been formed. Mean- 
time these nuclei, which have become very numerous, are evenly 



disseminated through the endoplasm forming the centres about each 
of which a crystal, an oil -vesicle, a vacuole, and granule are 

Fio. 24. 

Portion of a colony of Sphaerozoum neapolitanum about to form isospores. The spicules and 
"yellow cells" are omitted. The central capsule has disappeared, and only a thin peripheral 
ectoplasmic layer is present. Minute crystals are scattered through the endoplasm, and two- 
oil-globules (o) are shown. X 300. (After Brandt.) 

clustered. The whole endoplasm is now transformed into a mass 
of biflagellated spores. The central capsule suddenly disappears,, 
and the ectoplasm, which in the interval has undergone contraction 



Fio. 25. 

A, formation of isospores in Collozoum inerme. Two stages are shown on opposite sides of 
a central capsule. On the left side the nuclei and crystals are aggregated peripherally, but the 
central oil-globule is intact. On the right the nuclei are smaller and more numerous and the 
oil-globule is breaking down. B, formation of heterospores in the same shown by quadrants, 
a, early stage ; several grouped, modified nuclei and fat-granules ; between the groups are undif- 
ferentiated nuclei and endoplasm ; 6, c, and d are later stages. 

and degeneration, breaks to pieces. The colony descends and the- 
isospores swarm out, leaving (in the Collosphaeridae) the large 
crystals and the greater part of the pigment behind. Each is a- 



conical structure ('012 mm. long). From its pointed end spring 
the two cilia, one of which is usually held in a somewhat horizontal 
position, the other curving backwards and downwards. Near this 
end lies the nucleus, which has acquired, according to Brandt 
(10, p. 163), a certain differentiation. The broader end is filled 
with the crystal and granules (Fig. 26, E). 

Heterospwes, The formation of megaspores and microspores 
may proceed from the same (Sphaerozoidae) or separate colonies 

FIG. 26. 

Isospores and heterospores of Radiolaria. A, heterospores of Xiphacantha alata (Acantharia). 
B, isospores of the same. C and D, microspore and megaspore of Collozoum inerme. E, 
isospore of the same showing crystal and inclusions. F and G, megaspores of Sphaerozoum sp. 
H, microspores of the same. (After Brandt.) 

(Collosphaeridae). The process differs from the development of 
isospores in the presence of segregated nuclei, the differentiation in 
the nuclei of achromatic substance, and the dimorphism of the mega- 
and micro-nuclei. In the Collosphaeridae the full-grown vegetative 
.colony shows the first traces of heterospore- formation by the 
segregation of its homogeneous nuclei into groups of 2, 4, or 8. 
This arrangement is temporary, and very soon the nuclei are 
found arranged in several layers, each nucleus being now clearly 
composed of a highly refractive and achromatic ground-sub- 
>stance, in which are imbedded thread-like masses of chromatin. 


According to the colony under consideration so will these nuclei 
belong either to the microspore or megaspore. In the former the 
chromatin is disposed in stout granules and thick strands, in the 
latter in much smaller quantity. In other respects the colony 
behaves precisely as in the formation of isospores. 

In the Sphaerozoidae the formation of heterospores takes place 
both in small, apparently young, colonies that bear extracapsular 
bodies and also from full-grown vegetative colonies. In both cases 
many of the nuclei become segregated and differentiated, the endo- 
plasm in which they lie acquires distinctive characters, and the 
groups so formed are separated by undifferentiated plasma and 
nuclei (Fig. 25, B). The oil-globule becomes subdivided into a grape- 
like mass, which ultimately splits up into minute granules, and 
these are collected around the specialised nuclei. In the case of 
colonies bearing extracapsular bodies the whole of this bud becomes 
transformed into megaspores, the contents of the central capsule 
becoming microspores. In older colonies the endoplasm is con- 
verted into a vast number of portions, in each of which the differ- 
entiated nuclei are aggregated. These nuclei are, however, not all 
of one kind. Each collection is either meganucleate or micro- 
nucleate, and accordingly stains feebly or strongly. The contents 
of the capsule now becomes resolved into biflagellated megaspores 
and microspores, the ectoplasm degenerates and collapses, the 
central capsule deliquesces, and the spores become disseminated. 

Little is as yet known as to the formation of isospores and 
heterospores in other Radiolaria. In Acanthochiasma rubescens 
(Acantharia) Brandt records the early development of two kinds of 
bodies one with crystalloid inclusions, the other with lobulated 
masses of fat. The same observer has described the active spores 
of XipJiacantha alata and Acanthometra sicula. Two kinds of spores 
occur in these Acantharia (Fig. 26, A, B). Both are minute 
('004 mm. long), and provided with three cilia, which spring from 
the two poles of the spheroidal or pear-shaped body, but they differ 
in that the spores of any one individual either contain a minute 
crystal and few granules or many granules but no crystal. Both 
are provided with a starch-grain (see pp. 128), and traces of the 
yellow cells of the parent occur in the granular variety. It seems 
highly probable, therefore, that crystal-bearing isospores and granular 
heterospores occur in this sub-class as in the Spumellaria ; but 
although the results of more recent expeditions have extended very 
largely the number of Acantharia in which the early development 
of spores has been shown to occur, the free spores have not been 
again noticed; nor do we possess any exact observations on the 
flagellated bodies that have occasionally been seen in Nassellaria 
and Phaeodaria. 





Central capsule homaxonic, uniformly perforated by numerous similar 
and extremely small pores. Skeleton siliceous. Extra-capsulum volum- 
inous (except in Physematiidae). 

ORDER 1. Collodaria. 

Large monozoic forms not forming a true coenobium. Skeleton absent 
or spicular. 

FAMILY 1. PHYSEMATIIDAE. Large vacuoles confined to the endoplasm. 
No stratified concretions in the latter. No pigment. Few " yellow cells." 
Nucleus spherical, with smooth membrane and a few rounded nucleoli. 
Selected forms : Physematium miilleri, H. ; Thalassolampe margarodes, H., 
Mediterranean and Canary Islands ; Lampoxanthium murrayanum, Fowl., 
Faroe Channel. The genus Actissa of Haeckel is an early stage of growth 
of some species of this family. 

FAMILY 2. THALASSOPHYSIDAE. Large vacuoles extracapsular. 
Structure similar to that of the Thalassicollidae, but nuclear membrane 
usually tubercular or papillary. Reproduction by rapid and peculiar 
fragmentation (Fig. 21). Spores unknown. Selected forms : Thalas- 
siosolen atlanticus,Wolf. (28); Thalassophysa pelagica, H. (Fig. 1), Faroe 
Channel ; T. sanguinolenta, H. ; T. papillosa, H., Mediterranean and 
Canary Islands (often deformed by ingested Coccolithophoridae). For 
further account of this family see Brandt (25). 

FAMILY 3. THALASSICOLLIDAE. Nuclear membrame smooth and 
spherical. Stratified concretions present in the endoplasm. Multiplica- 
tion by binary fission, by isospores, and by heterospores (see Fig. 2 ; 
Brandt [25, 25a, and 26]). Selected forms : Thalassicolla nucleate/,, Hux., 
Valencia Harbour, Faroe Channel, and cosmopolitan ; T. spumida, H., 
Canary Islands ; T. pellucida, H., cosmopolitan. 

FAMILY 4. THALASSOTHAMNIDAE, Hacker (37). Skeleton in the 
form of a large single radiate spiculum or of a double spiculum. Central 
capsule sometimes spherical, characteristically lobed or branched. 
Nucleus complex. Nuclear membrane crenate (Fig. 14). Endoplasm with 
stratified inclusions. Selected forms : Thalassothamnus ramosus, Hack., 
Antarctic ; Cytocladiis spinosus, Schroder (Fig. 10), Japan Seas (38). 

FAMILY 5. OROSPHAERIDAE. Protoplasm organised as in the preceding 
family. Skeleton a perforated shell with branched and thorny spines. 
Orosphaera, H., deep water of mid-Atlantic. This family has been re- 
moved by Hacker (37) from the Phaeodaria, with which group Haeckel 
associated it ; but if the presence of a phaeodium, astropyle, and parapyles 
is confirmed, its systematic position will have to be revised. 

1 The number of genera and species in this class is so large that only a selection 
can be referred to here. North Atlantic forms have been chiefly selected. 


ORDER 2. Sphaerozoa. 

Colonial forms. 

FAMILY 1. SPHAEROZOIDAE. Both mega- and microspores developed 
in the same individual. A lattice-shell absent. Selected forms: 
Collozoum inerme, Norway (Figs. 3, s, and 25) ; C. pelagicum, Shetlands ; 
Sphaerozoum ovodimare, Faroe Channel. 

FAMILY 2. COLLOSPHAERIDAE. Mega- and microspores in separate 
individuals. Skeleton, when present, takes the form of a lattice-shell 
with or without associated spicules. Selected forms : Oollosphaera huxleyi, 
Mediterranean (Fig. 23) ; Choenicosphaera murrayana, Shetlands. 

This order is treated fully by Brandt in his Monograph (10) and (22). 

ORDER 3. Sphaerellaria. 

SUB-ORDER 1. SPHAEROIDEA. Central capsule and shell (or shells) 
spherical. Selected forms : Hexalonche philosophica, H., Faroe Channel ; 
Hexacontium enthacanthium, Jorg. ; H. pachydermum, Jorg., North Sea ; 
Hexadoras borealis, Clev., North Sea ; Echinomma, leptodermum, Jorg., 
Norway and Sweden ; Rhizoplegma boreale, Clev., Norway. 

SUB-ORDER 2. PRUNOIDEA. Central capsule and shell elliptical or 
cylindrical ; often with transverse constrictions. Selected form : Pruno- 
carpus datura, H., Faroe Channel. 

SUB-ORDER 3. DISCOIDEA. Central capsule and shell discoid or 
lenticular; often much flattened. Selected forms: Trochodiscus 
heliodes, Cler., North Sea ; T. echiniscus, H. ; Lethodiscus microporus, H. ; 
Astrosestrum acanthastrum, H. ; Spongodiscus favus, Ehr., Faroe Channel. 

SUB-ORDER 4. LARCOIDEA. With lentelliptical central capsule and 
shell. Selected forms : Lithelius minor, North Sea ; L. arborescens, H., 
Faroe Channel ; Phorticium pylonium, H., Norway and Sweden. 

SUB-ORDER 5. SPHAEROPYLIDKA. With basal or basal and apical 
pylome (large opening to the shell). See Dreyer (15). 


Radiolaria in which the skeleton is composed neither of the so-called 
horny acanthin nor of silica, but (in many cases) of strontium sulphate. 
The central capsule is perforated uniformly or in networks and segregated 
pores. The skeleton has the form of spicules radiating from a central 
point within the capsule (Acanthometrida). Rarely a fenestrated 
extracapsular skeleton is added (Acanthophractida). 

ORDER 1. Acanthometrida. 

SUB-ORDER 1. ACTINELIIDA. With 10-200 radial or diametral spines 
not arranged according to Miiller's Law (p. 132). 

FAMILY 1. ASTROLOPHIDAE. Spines radiating from a common centre. 
Genus 1. Adinelius. All spines of equal length and similar shape. A. 
purpureus, H., Mediterranean. Genus 2. Astrolophus. Spines of unequal 



It is probable that further investigation of the Actineliida will clear 
up the anomalies that at present attach to their isolated position. They 
are regarded by Haeckel as the ancestral stock of the whole Itadiolaria. 
The family Litholophidae which he associated with them is now regarded 
as composed of growth-stages of the genus A canthonia. 

FAMILY 2. ACANTHOCHIASMIDAE. "With ten or sixteen diametral 
spines irregularly arranged. Genus Acanthochiasma. With ten spines, 
A. fusiforme, found near Plymouth and in the North Sea. A. cruciata, 
A. krohnii, generally distributed in the Atlantic. 

SUB-ORDER 2. ACAXTHOXIIDA. With twenty spines arranged in four 
zones of five spines to each (Muller's Law). 

FAMILY 1. ACANTHOMETRIDAE. Spicules circular in transverse 
section. Genera Acanthometron ; proximal end of spines without flange ; 
A. pellucidum, N. and E. Scotland. Phyllostaurus, with flange ; Ph. 
quadrifolius, abundant in North Atlantic. 

FAMILY 2. ZYGACANTHIDAE. Spines compressed and double-edged, 
lanceolate in section. Genus Zygacantha, without flange at base of 
spines ; Z. septentrionalis, North Atlantic. 

FAMILY 3. ACANTHONIIDAE. Spines cruciform in cross section. 
Genus Acanthonia ; A. rnulleri, N. Scotland and North Sea; A. 
ligurina, W. coast of Greenland ; Acanthonidium ; A. echinoides, North 
Sea, Faroes and Norway ; A. pallidum, N. and E. coasts of Scotland. 

FAMILY 4. AMPHILONCHIDAE. Two opposite spines much larger than 
the rest. Genus Amphilonche. A. belonoides, generally distributed 
in the Atlantic. For the exotic family Lithopteridae, see Haeckel's 
Monograph (11). 

ORDER 2. Acanthophractida. 

SOB-ORDER 1. SPHAEROPHRACTA. With twenty radial spines of 
equal size. Shell spherical. 

FAMILY 1. SPHAEROCAPSIDAE. Shell composed of very numerous 
small plates each with a single pore. Genera 1. Sphaerocapsa. Sph. 
cruciata, Faroes, North Atlantic. 2. Astrocapsa. A. tritonis and A. 
coronata, Faroes and North Atlantic. 3. Porocapsa. P. murrayana. 4. 
Cannocapsa. G. osculata, Faroe Channel and North Atlantic. 

FAMILY 2. DORATASPIDAE. Shell composed of the meeting branches 
of two to four apophyses given off by the twenty radial spines. Seventeen 
genera are known, mostly from equatorial or southern waters. 

FAMILY 3. PHRACTOPELTIDAE. Shell double ; the inner one 
enclosed by the central capsule. No genera known from northern 

SUB-ORDER 2. PRUNOPHRACTA. Two or six spines much larger than 
the rest. Shell not spherical. 

FAMILY 1. BELONASPIDAE. Shell ellipsoidal. Two enlarged spines. 
The genus Platnaspis occurs in North Atlantic and Mediterranean. 

FAMILY 2. HEXALASPIDAE. Shell lentelliptical. Six enlarged 
spines. The genus Hexaconus is known from the North Atlantic. 

FAMILY 3. DIPLOCONIDAE. Shell diploconical with two opposite 
large funnels (the sheaths of the two enlarged spines). Pseudopodia con- 


fined to the two polar apertures. The genus Diploconus is known from 
the Mediterranean. 


Radiolaria with monaxonic central capsule that bears at one pole a 
porous plate forming the base of an inwardly directed cone. 

SOB-LEGION 1. Plectellaria. 

Without a complete lattice-shell. 

ORDER 1. PLECTOIDEA. Skeleton a basal tripod (Fig. 5). Selected 
forms : Plagiacantha arachnoides, Clap., W. coast of Norway, North Sea ; 
Plagiocarpa procyrtella, EL, North Atlantic, Iceland ; Hexaplagia arctica, 
H., Greenland ; Polyplagia novenaria, H., Faroe Channel, North Atlantic ; 
Plectophora arachnoides, H., and PI. novena, H., North Atlantic and Faroe 
Channel, North Sea. 

ORDER 2. STEPHOIDEA. Skeleton a sagittal ring, and usually no 
tripod. Selected forms : Lithocircus annularis, Mull. ; Cortiniscus 
iypicus, H. ; Eucoronis nephrospyris, H. ; all cosmopolitan. 

SUB-LEGION 2. Cyrtellaria. 

Skeleton a complete lattice-shell (cephalis). 

ORDER 1. SPYROIDEA. Cephalis bilocular with cephalic construction. 
Almost exclusively southern forms. 

ORDER 2. BOTRYOIDEA. Cephalis multilocular. Selected forms : 
Sotryocampe inflata, Ehr., cosmopolitan ; Phormobotrys hexaihalomia, H., 

ORDER 3. CYRTOIDEA. Cephalis single, without constrictions or lobes. 
Selected forms : Tridictyopus elegans, Hert., Mediterranean ; Cornutella 
lathrata, Ehr., cosmopolitan ; Cyrtocalpis obliqvM, H., cosmopolitan ; 
Lithomelissa thoracites, H., cosmopolitan ; L. setosa, H., Norway ; Eucecry- 
phalus gegenbauri, H., cosmopolitan ; Carpocanium diadema, H., cosmo- 
politan ; Dictyocephalus ocellatus, H., Faroe Channel ; Dictyophimus clevei, 
Jorg., Norway ; Theoconus ariadnes, H., cosmopolitan ; Cladoscenium 
tricolpium, Norway ; Clathrocyclas craspedota, Norway. 


Radiolaria in which the central capsule is double and usually 
possesses a chief aperture (astropyle) and two accessory apertures (para- 
pyles). A dense resistant pigment (phaeodium), probably of excretory 
nature, accumulates in the extracapsulum. The skeleton is siliceous and 
.often made up of hollow tubes. 

ORDER 1. Phaeocystina. 

The skeleton consists of isolated spicules. 

FAMILY 1. AULACANTHIDAE. Skeleton of tangential needles and radial 
; hollow rods. Selected forms : Aulacantha scolymantha, H., Hebrides, 



Faroe Channel, Shetlands ; Aulographis zetesios, Borg. ; A. furcellata, 
Wolf., Faroe Channel ; Au. tetrancistra, H., Norway ; Aulodendron boreale, 
Wolf., Faroe Channel. 

ORDER 2. Phaeosphaeria. 

Skeleton composed of an extracapsular shell or of two concentric 
shells separated by the extracapsulum. Outer shell usually spherical. 

FAMILY 1. SAGOSPHAERIDAE. Outer shell a lattice-work with 
triangular or areolar meshes. Selected forms : Sagena ternaria, H. ; 
Sagosphaera trigonilla, H., cosmopolitan ; Sayenoarium sp., Jorg, Norway. 

FAMILY 2. AULOSPHAERIDAE. An outer lattice-shell alone present, 
the hollow bars of which contain septa. Selected forms : Aulosphaera 
flexuosa, H., Faroe Channel ; Auloscena verticillatus, H., Norway ; Aulotractus 
fusulus, H., Faroe Channel, Hebrides. 

FAMILY 3. CANNOSPHAERIDAE. Inner and outer lattice- shells present, 
interconnected by radii. Cannosphaera antarctica, H., bipolar form. 

FAMILY 4. POROSPATHIDAE. Inner shell alone present, composed of 

two finely grained membranes ; elliptical 

*EXO. or ovoid. Mouth at the end of a curved 



ORDER 3. Phaeogromia. 



A single simple shell present, variable 
in shape, but always provided with a 
projecting peristome. 

monaxonic, composed of two layers which 
exhibit an extremely fine diatomaceous 
graining. Peristome toothed. Selected 
forms : Lithogromia silicea, H., Faroe 
Channel ; Protocystis tritonis, H., Faroe 
Channel, Shetlands, North Sea ; Pr, 
tridens, H., Norway and Sweden ; Pr. 
harstoni, Murray, Norway ; Pr. xiphodon, 
H., Faroe Channel ; Challevgeron trioden, 
balfouri, golfense, johannis, armatum (Fig. 
27) ; Cadium melo, Clev. ; Pharyngella 
gastrula, H. ; Entocannula hirsuta, H. ; 
Faroe Channel. 

shell alveolar. Peristome with articulated 

surroundedby processes and its aborai f eet ^ secondary shell may be developed 
surface bears a crest (Exo). The central . . * J 

capsule possesses two astropyles (As), in relation to the phaeodium. 

two parapyles, and two nuclei. The A q 11 t (avertm-ncr 0-1 mm 

brown phaeodellae (Ph) are shown. * ln dil S ^averaging U 1 mm, 

(From a living specimen, after Borgert.) in diaui.), with primary shell and few 

radial spines. Phaeodium in primary 

shell. Euphysetta nathorsti, Clev., North Sea, Scotland ; Mediisetta 
tiara, H., Faroe Channel. 

B. Small forms (0-8--3 mm.), with hooded primary shell provided 

Fia. 27. 

Challengeron armatum, Borg. x 225 
The mouth (M) of the perforated shell is 



with six long radial spines. Phaeodium still in the primary shell. 
Gazelletta, Fowler. 

C. Large forms, with conical shell, completely filled by central 

FIG. 28. 

Atlanllcella craspedota, 
Borgert. In this newly 
discovered family of Phaeo- 
daria the central capsule 
(C.c) is a large inflated 
4 - lobate structure. The 
skeleton consists of a me- 
dian hollow part (M.Sk) and 
of four pendent septate 
arms (Sp). The black area 
is the phaeodium (Ph). 
x 50. (After Borgert.) 


capsule, which is converted into a swim-bladder. A diaphragm, perfor- 
ated (Hacker [37]) by several astropyles and parapyles, separates 
endoplasm from ectoplasm (Fig. 12). Phaeodium outside primary 


FIG. 29. 

Planktonetta atlantica, Borgert. 
(After Fowler.) x 66. The entire 
animal is shown as seen in a pre- 
served specimen. One pair of arms 
is omitted. The central capsule 
(End) is invested by a skeletal 
membrane and forms a float. The 
arms are embedded in the phaeo- 
dium (Ph) and attached to this 
is the outer shell (F), comparable 
with that of Medusetta and Atlanti- 
cella. A section through this 
animal is seen at Fig. 12, p. 120. 


shell, with intra-phaeodial skeleton. A float present. Planktonetta 
atlantica, Borg., Faroe Channel (29, 37). 

D. Large forms, without primary shell. Central capsule a swim- 
bladder. Diaphragm and phaeodial skeleton as in preceding sub-family. 
Secondary shell projecting over peristome. No float. Nationaletta. 


E. Mid-sized forms, without primary shell. Secondary shell with 
four arms. Atlanticella. (Fig. 28.) Borgert (21). 

FAMILY 3. CASTANELLIDAE. Primary shell two -layered and com- 
posed of (1) extremely delicate tangential siliceous needles; (2) the 
two conjoined limiting membranes of the two layers, united by (3) a 
porcellanous impregnation. Selected form : Castanidium apsteini, 
bipolar (36). 

FAMILY 4. CIRCOPORIDAE. Shell composed as in Family 3, but 
spherical, polyhedral, or multipolar (36). 

FAMILY 5. TOSCARORIDAE (Fig. 30). Shell rarely spherical, gener- 
ally monaxonic. Nucleus elongated with sigmoid chromatin band. 
(Borgert [2 la].) 

FIG. 30. 

Tuscaroridae. A, Tuscarusa globosa, Borgert, showing the peristomial hollow spines ; 
the rest are broken off. x 39. B, Tuscarora nationalis, Borgert, showing the two central 
capsules in the shell. Each capsule contains a bent nucleus, x 24. (After Borgert.) 

ORDER 4. Phaeoconchia, H. 

Central portion of the skeleton in the form of two valves, free or 
hinged together. 

FAMILY 1. CONCHARIDAE, H. With thick valves, which are devoid 
of an apical cupola and of radial tubes. Equatorial and southern 

FAMILY 2. COELODENDRIDAE. "With extremely thin valves, each of 
which bears a cupola and tubular processes. Goelodendron ramosissimum, 
Faroe Channel and cosmopolitan. 

FAMILY 3. COELOGRAPHIDAE. Each cupola provided with a hollow 
process (rhizocanna), which communicates with the cupola by a paired 
or unpaired frenulum. Radial tubes strongly developed, sometimes 
forming an outer bivalved mantle. The largest and most complex 


Fio. 31. 

Coelothamnus davidoffii, Btitschli ; one of the Phaeodaria. Entire animal drawn from a dead 
specimen, x 4. Sixteen radii spring from the bivalve shell (S) which encloses the central 
capsule. The ectoplasm (E) is shown investing the skeleton which supports it on the anchor- 
like extremities of its tufted appendages. (After Btitschli.) 

Radiolaria (20-30 mm. in diara.). Selected forms: Coeloplegma 
murrayanum, H. (Fig. 32) ; G. tritonis, H., Faroe Channel. 


Fio. 32. 

Central capsule and adjacent structures of Codoplegma murrayanitm, H.; one of the Coelo- 
graphidae. The bivalve shell (S) supports the hollow-branched galea (G), in which the phaeo- 
dellae are seen emerging through the aperture (R) of the nasal tube (rhizocanna). The astropyle 
(As) is drawn out into a tube. 


1. Ehrenberg, Ch. G. Monatsberichte d. Berliner Akad. 1844-73. 

2. - - (Fossil Species.) Abhandl. d. k. Akad. Berlin, 1872, pp. 131-397. 

3. Huxley, T. H. (Thalassicolla.) Annals and Mag. Nat. Hist. vol. viii., 

1851, pp. 433-442. 


4. Miiller,. J. (Fundamental Treatise.) Abhaudl. d. Berliner Akad. 1858, 

pp. 1-62. 

5. Haeckel, E. Die Radiolarien. Berlin, 1862. 

6. Cienkowski. (Yellow Cells.) Archiv f. mikros. Anat. vii., 1871, pp. 372-381. 

7. Hertwig, R. (Structure of Radiolaria. ) Jenaische Denkschriften, vol. ii., 

1879, pp. 129-277. 

8. Biitschli, 0. (Skeleton of Nassellaria.) Zeit. f. wiss. Zool. vol. xxxvi., 

1881, pp. 485-540. 

9. (Monograph.) Bronn's Thierreich, Protozoa, vol. i., 1885, pp. 332-478. 

10. Brandt, K. (Sphaerozoa.) Fauna v. Flora d. Golfes von Neapel, vol. xiii., 

10a. (Zooxanthellae.) Mittheil. Stat. Neapel, iv., 1883. 

11. Haeckel, E. (Monograph.) Challenger Reports, vol. xviii., 1887. 

12. Lankester, E. Ray. Radiolaria in Encyclopaedia Britannica, Art. 

"Protozoa," pp. 20-23 of reprint. 

13. Famintzin, A. (Life -History, Food, and Yellow Cells of Sphaerozoa.) 

Memoires de 1'Acad. Sci. St. Petersbourg, 7th series, vol. xxxvi. No. 16, 
1889, p. 21. 

14. Verworn. (Thalassicolla.) Pfliiger's Archiv f. Physiologic, vol. li., 1891, 

p. 118. 
14a. (Hydrostatics.) Ibid. vol. liii., 1893, pp. 140-155. 

15. Dreyer, F. (Evolution of Radiolarian Skeleton.) Jenaische Zeit. f. 

Naturwiss. vol. xxvi., 1892, pp. 204-468. 

16. Karawiew. (Fission in Aulacantha.) Mem. Soc. Natur. Kiew. vol. xv., 


17. Borgert, A. (Reproduction of Tripylaria.) Annals and Mag. Nat. Hist. 

(6), xviii., 1896, pp. 422-426. 

18. (Fission in Aulacantha.) Spengel's Zool. Jahrb. Anat. vol. xiv., 

1900, pp. 203-274. 

19. (North Atlantic Tripylaria.) Nordisches Plankton, Lief, i., 1901, 

pp. 1-52. 

20. (Tripylaria of the German Plankton Expedition. ) Zool. Jahr. Syst. 

vol. xix., 1904, pp. 733-760. 

21. (Atlanticellida.) Ergeb. Plankton-Expedition, vol. iii., 1906. 

21a. (Tuscaroridae. ) Ibid. vol. iii., 1906. 

22. Vernon, H. M. (Respiration in Collozoum.) Journal of Physiology, 

vol. xxi., 1897, p. 443. 

23. Brandt, K. (Bionomics of Acantharia.) Ergebnisse d. deutschen Plankton- 

Expedition, vol. i., 1892, p. 338. 

24. (Hydrostatics.) Zool. Jahrbiicher Syst. vol. ix., 1895, pp. 27-74. 

25. (Thalassophysidae.) Archiv f. Protistenkunde, vol. i., 1902. 

25a. (Division of Thalassicolla.) Mitteil. d. Vereins Schlesw.-Holstein. 

Aerzte, 12. Heft, 1890. 

26. (Thalassicollidae.) Ibid. vol. vi., 1905, pp. 245-271. 

27. (Classification of Sphaerozoa.) Zool. Jahrb. Suppl. vol. viii., 1905, 

pp. 311-352. 

28. Wolfendcn, R. N. (Radiolaria of Faroe Channel and Shetlands.) Journal 

Marine Biol. Assoc. N.S. vol. vi., 1902, No. 3. Trans. Linn. Soc. vol. x., 
pt. 4, 1905. 

29. Fowler, G. H. (Planktonetta.) Quart. Journ. Mic. Sci. (2), vol. xlvii., 

1903, pp. 133-143. 


30. Fowler, G. H. (GazellcUa.) Quart. Journ. Mic. Sci. (2), vol. xlviii., 1904, 

pp. 483-488. 

31. - - (Radiolaria of Faroe Channel.) Proc. Zool. Soc. 1896-98, pp. 991, 523, 


31a. Popowsky, A. (North Atlantic Acantharia.) Nordisches Plankton, Lief, 
iii., 1905, pp. 43-69 ; Lief, v., 1906. 

32. (Acantharia.) Ergeb. Plankton -Expedition, 1904; Appendix in 

Archiv f. Protistenkimde, vol. v., 1905, pp. 339-357. 

33. Schcwiakoff, W. (Skeleton, Myonemes, and Flotation of Acantharia.) 

Me'moires de 1'Acad. des Sci. St. Petersbourg, vol. xii., 1902, No. 10. 

34. Immermann, F. (Aulacanthidae.) Ergeb. Plankton-Expedition, vol. iii., 


35. Hacker, V. (Biological Significance of Tripylarian Skeleton.) Jenaische 

Zeitschrift f. Naturwiss. vol. xxxix., 1905, pp. 581-648 ; Zeit. f. wiss. 
Zool. vol. Ixxxiii., 1905, pp. 336-375 ; Archiv f. Protistenkunde, vol. ix., 
1907, pp. 139-169. 

36. (Challengeridae, Tuscaroridae, Circoporidae of the Valdivia Expedi- 
tion.) Archiv f. Protistenkunde, vol. viii., 1906 ; and Verhandl. deutsch. 
zool. Gesellschaft, vol. xiv., 1906, pp. 122-156. 

37. (Thalassothamnidae, Medusettidae. ) Zool. Anzeiger, vol. xxx. , 1906, 

No. 26, pp. 878-895 (16 figs.). 

38. Schroder, 0. (Cytocladus.) Zool. Anzeiger, vol. xxx., 1906, pp. 448 and 


39. ButscJili, G. (Strontium Sulphate in Skeleton of Acantharia, etc.) Zool. 

Anzeiger, vol. xxx., 1906, No. 24, pp. 784-789. 

40. Delap, M. and C. (Irish Thalassicollidae.) Scientific Investigations, Irish 

Fisheries, 1905 (vii.) [1906]. 

41. Keeble, F., and Gamble, F. W. (Green Cells of Convoluta. ) Quart. Journ. 

Micr. Sci. vol. 1L, 1907, pp. 167-219. 

42. Schaudinn, F. (Trichosphaerium.) Abhandl. d. kgl. preuss. Akad. Wiss. 

Berlin, Supplement, 1899. 

43. Patter, E. (Respiration of Protozoa.) Zeit. f. allgemeine Physiologic, 

vol. v., 1905, pp. 566*612. Ibid. vol. vii. pp. 46-53. 

44. Hinde, J. G. (Fossil Radiolaria.) Quart. Journ. Geol. Soc. vol. Iv. pp. 


45. Johnstone, J. (Summary of Recent Work on Marine Nitrogenous Food- 

Stuffs.) Science Progress (N.S.), vol. ii., 1907, pp. 191-210. 

46. Klebs, G. (Yellow Cells and Peridinians.) Bot. Zeitung, vol. xlii., 1884, 

p. 721. 

THE PEOTOZOA (continued) 



Order 1. Monadidea. 

Tribe 1. Pantostomatina. 
Sub-Tribe 1. Holomastigoda. 
^ 2. Rhizomastigoda. 
Tribe 2. Protomastigina. 

Sub-Tribe 1. Monomastigoda. 
2. Paramastigoda. 
3. Heteromastigoda. 
4. Isomastigoda. 
Tribe 3. Polymastigina. 
Sub-Tribe 1. Trimastigina. 
,, 2. Monostomatina. 
3. Distomatina. 
4. Lophomonadina. 
Order 2. Euglenoidea. 
Tribe 1. Euglenina. 
2. Astasiina. 
3. Peranemina. 
Order 3. Chromomonadidea. 
Tribe 1. Chloromonadina. 
2. Chrysomonadina. 
,, 3. Cryptomonadina. 
Order 1. Craspedomonadina. 

2. Phalansteriina. 
Order 1. Chlamydomonadina. 

2. Volvocina. 


Tribe 1. Gymnodiniaceae. 

,, 2. Prorocentraceae. 

3. Peridiniaceae. 



1 By Arthur Willey, F.R.S., and Prof. S. J. Hickson, F.R.S. 


THE unicellular organisms which are associated in the class Mastigo- 
phora or Flagellata in the wide sense, comprise a very heterogeneous 
assemblage of forms, having in common the possession of certain 
characteristic traits of organisation (a single nucleus, one or more 
contractile vacuoles, one or more flagella), and further united together 
phyletically by the occurrence of transitional or annectant types. 

Our knowledge of the group dates back to the time of Anton 
Leeuwenhoek, at the beginning of the eighteenth century, while 
the foundation of the modern system may be safely attributed to 
the labours of Christian Gottfried Ehrenberg during the early part 
of last century (1830-1838). 

From the most general point of view the peculiar biological 
interest of the Mastigophora rests upon the fact that, in this more 
than in any other class of Protista, the formal distinctions which 
are commonly drawn between the animal and vegetable kingdoms 
vanish. It was formerly a question whether such and such an 
order of Mastigophora should be reckoned among the unicellular 
Algae or among the Protozoa, but this controversy is now practi- 
cally over, and biological disquisitions upon the group are equally 
at home and equally necessary in zoological and botanical treatises 
and journals. 

When an organism possesses a green colour, due to the presence 
of chloroplasts stained with chlorophyll, has a cell-wall that gives 
the chemical reactions of cellulose, and is devoid of a mouth for the 
ingestion of solid food, it is usually regarded as a plant. When, 
on the other hand, an organism bears no chlorophyll, has no cell- 
wall, or has a cell-wall that does not give the cellulose reaction, 
and possesses a mouth for the ingestion of solid food, it is usually 
regarded as an animal. 

If it were possible to divide the Mastigophora into two 
divisions, one containing all those forms provided with a mouth 
and devoid of chlorophyll and a cellulose cell-wall ; and the other 
containing all those forms without a mouth, bearing chlorophyll and 
surrounded by a cellulose cell-wall, then the former division could 
be assigned to the animal kingdom and the latter to the vegetable 
kingdom. Such a division would, however, be thoroughly un- 
scientific and unnatural. It could only be made by deliberately 
ignoring obvious genetic relationships. Moreover, such a division 
would leave out of account a number of organisms particularly 
Monadidea which fail to fulfil all the conditions for their admission 
into either of the divisions. 

It is not by the study of any one stage of the life-history of 
these organisms that it is possible to arrive at any clear conception 
of the best distinction that can be drawn between the animal and 
vegetable kingdoms. 

The study of the whole life -history of some of the lower 


animals and plants, however, suggests a line of distinction which is 
perhaps more in accordance with a natural system of classification. 

In the life -history of Ulothrix, one of the Ulotrichaceae, an 
example of an organism that is universally regarded as a plant, we 
find two forms of cells. There are the cells of the filamentous 
thallus, protected by a cell-wall, containing chlorophyll, and, under 
favourable conditions, growing and increasing in number by fission ; 
and there are the cells provided with two or four flagella that 
escape from their cellulose investments and eventually conjugate to 
form a motionless zygospore. 

If we compare this with the life-history of such a form as 
Mastigella, one of the Mastigophora that is universally regarded as 
an animal, we find that during the phase of life when growth and 
repeated multiplication by fission occurs the organism is actively 
moving about by means of its flagellum or its pseudopodia, and that 
the gametes that it gives rise to are also active and flagellate. 
Any period in the life-history of Mastigella when active movements 
cease is not, as in the case of Ulothrix, a period of vegetative 

If we regard, then, as marks of distinction between an animal 
and a plant (1) that the stage of growth and reproduction of 
somatic cells by fission is marked by a period of active mobility in 
the former, and of stability in the latter ; and (2) that the flagellate 
cells of the latter do not grow and divide by fission, but conjugate 
and give rise immediately to a sedentary zygospore, whereas in the 
former the flagellate cells may grow and divide by fission, we 
represent a consideration which has had considerable weight in 
determining the action of zoologists in including the Mastigophora 
in the animal kingdom. But the boundary thus drawn, even if it 
is the best that can be drawn, is itself subject to some exceptions. 

In some of the Chlamydomonadina we find, for example, that 
flagellate individuals similar in general characters to the gametes 
form a gelatinous investment, withdraw their flagella, grow and 
divide repeatedly by fission. It is difficult to distinguish this phase 
of life (the " palmella-stage," as it is called) from a true plant under 
the terms of our definition. The close relation of the Chlamy- 
domonadina to the Chromomonadina, however, is so clear that to 
separate them by placing one order in the vegetable kingdom and 
the other in the animal kingdom on this ground alone would be 

The life-history of the Chlamydomonadina seems to support 
very strongly the view that some of the families of the lower Algae 
have sprung from a flagellate ancestry, but it does not justify the 
assumption that the vegetable kingdom as a whole owes its origin 
to the class Mastigophora. 1 

1 See Blackman and Tansley (2), and West (22, pp. 32 et seq.). 


It is principally in respect of their modes of nutrition that the 
Mastigophora appear to betray the mixed animal and vegetable 
properties, so that as a class they have come to be regarded as 
mixotrophic micro-organisms. The four possible methods of ali- 
mentation holozoic, parasitic, saprophytic, and holophytic are all 
to be met with among the members of this protean series, either 
separately or in combination. When a single species can vary its 
metabolism in adaptation to its immediate environment, for example, 
according as it is exposed to or deprived of the influence of light, 
it is said to be mixotrophic in the strict sense of the term (Pfefl'er). 

It is not always easy to assert positively in Avhat manner food is 
conveyed into the protoplast (protoplasmic body of the cell), but it 
is certain that holozoic nutrition is often associated in the same 
species with saprophytic (Monadidea), saprophytic with parasitic, 
saprophytic with holophytic (Euglenoidea), and, more rarely, 
holozoic with holophytic (Chromulina). Sometimes three methods 
are found in combination holozoic, saprophytic, and holophytic 
(Ochromonas). It may be stated as a general rule that all Lisso- 
flagellata (i.e. true Flagellata in the restricted sense) are capable of 
saprophytic nutrition, that is to say, of absorbing nutriment from 
putrescent substances in an aqueous medium, but that this source 
of food is usually accessory to some other essential means of 
nourishment. Where saprophytism is the sole condition of exist- 
ence, as in the case of the Astasiina, there is reason to regard it 
as a secondary state derived, in the particular instance quoted, 
from a condition of holophytism. 

The parasitic forms may be described broadly as falling inta 
three categories : ectoparasites (Costia, Stylochrysalis, Silicoflagellata) ;. 
endoparasites (species of Hexamitus, Megastoma, Tetramitus, Tricho- 
mastix, Trichomonas, Trichonymphidae) ; and haematozoa (Trypano- 
soma, Herpetomonas). 

The non-parasitic Mastigophora are either free -swimming or 
sessile, solitary or colonial in habit. 

Some species are capable of temporary fixation by means of a, 
protoplasmic stalk either of pseudopodial (e.g. Oicomonas sp., Fig. 5 
(31)) or of flagellar (e.g. Bodo sp.) origin. Some solitary free forms- 
are closely related to solitary fixed forms (e.g. Euglena, and Ascoglena), 
and many free-swimming colonial genera have sessile representatives- 
(e.g. Dinobryon and Hyalobryori). 

The form of association of individuals in the colonies varies 
within limits, and there is a great amount of parallelism in this 
respect between members of different orders. An entire colony or 
coenobium may attain to a certain degree of individuation, which is 
most marked in the Volvocina, but is not wanting in other groups, 
as is evident from the co-ordinated movements which they execute 
and from the fact that the whole coenobium may undergo binary 


fission (Uroglena). On the other hand, the units often retain a 
facultative independence, and the coenobium may then undergo 
dissociation (Synura). 

The principal forms of association of individuals are the follow- 
ing : 1. Linear aggregates, e.g. Hirmidium, Chlorodesmus, Ceratium; 

2. Rosettes, e.g. Bicosoeca socialis, Cydonexis annularis, Gonium pedorale ; 

3. Plates, e.g. Proterospongia, Platydorina ; 4. Spherical aggregates, e.g. 
Sphaeroeca, Uroglena, Volvox ; 5. Dendroid associations, e.g. Dinobryon, 
Hyalobryon, Poteriodendron, Anthophysa, Ehipidodendron, Dendromonas, 

Of the above colonial assemblages it is to be remarked that the 
dendroid form is the most polymorphic in actual appearance. As 
for transitional forms, it is not difficult to construct a series, while 
analogies are stupefying in their abundance. Thus a biserial linear 
aggregate like Chlorodesmus in comparison with a rosette like Cydo- 
nexis is absolutely paralleled by species of the pelagic Ascidian, Salpa. 
A transition from a rosette to a plate is afforded by Gonium, and 
from a rosette to a spherical aggregate by the volvocine genus 
Stephanosphaera, in which the units are arranged in a rosette 
though surrounded by a common gelatinous envelope. 

The Mastigophora as a class may be defined broadly as uni- 
nucleated Protista which perform their movements by means of one, 
two, or several flagella, usually arising at or near the anterior end, 
i.e. the end which is directed forwards during locomotion. The typical 
motion of the flagellum has been described as one of circumduction 
(Delage), by which the cell is drawn along at the same time that 
it rotates about its axis. The flagellum of a typical Flagellate 
Infusorian is therefore a tractellum, as opposed to the tail of a 
spermatozoan, which is a pulsellum. 1 It acts, however, as a pulsellum 
in exceptional cases among the Monadidea, and with the Choano- 
flagellata when they quit their attachment in order to effect change 
of position. 

According to the number, position, and proportions of the 
flagella we recognise monomastigote forms, with a single porrect 
flagellum ; paramastigote, with one or two small accessory flagella at 
the base of the main one ; isomastigote, with from two to four equal 
flagella ; heteromasligote, with divergent flagella, one directed forwards 
or transversely, the other directed backwards ; polymastigote, with 
more than four flagella ; to which may be added holomastigote forms, 
with numerous flagella distributed over the entire surface of the 
cell. The disposition of the flagella has a distinct systematic 
importance, but of much more limited application than was formerly 

1 The terms " tractellum " and " pulsellum " were suggested by Prof. Lankester. 
In some elongate metabolic species (Astasiina) the tractellum is directed straight 
forwards, and only the apical portion of it executes rapid vibrations, drawing the body 
.along without rotation. 


supposed, since the phenomenon of parallelism is as strikingly dis- 
played in this respect as in the manner of formation of colonies. 

The heteromastigote condition merits particular notice since it 
characterises an entire sub -class (Dinoflagellata), where the one 
flagellum is transverse, usually lying in an annular depression, while 
the other is longitudinal and is also partially protected by a groove, 
but extends backwards freely (Fig. 10). This is a special mani- 
festation of the heteromastigote condition, but equally interesting 
examples occur in many families of Lissoflagellata, where the 
anterior flagellum is normally directed forwards (tractellum) and 
the posterior flagellum which arises from the body of the cell close 
to the former is trailed behind. The posterior flagellum in these 
cases exerts a directive and modifying influence upon the move- 
ments of the Infusorian, serving also as an anchor and sometimes as 
a spring promoting a rapid jerking movement of leaps and bounds 
like the tail of a Podurid. 

The posterior flagellum of heteromastigote Mastigophora may 
be aptly described as a gubernaculum (Fig. 7 (10)) and referred to by 
that term. 

The flagellum is usually so extremely attenuated that it is 
very difficult to discover any structure in it, but as its base 
may often be traced from the surface through the ectoplasm to the 
endoplasm, it seems probable that it 
consists of an axial filament derived 
from the endoplasm and a delicate 
cortical sheath derived from the ecto- 
plasm. It is interesting to note that 
in the Ehizomastigoda there is an 
endoplastic axial filament in the pseudo- 
podia (Fig. 1). It is impossible to 
draw any morphological line of dis- 
tinction between a flagellum and a 
cilium, and in the Lophomonadina, for 
example, the vibratile processes have Fia * 

been interpreted as flagella by those Anffl^ofS'SUlS 
who regard this group as belonging g^5& ffi 5SS?K! 

to the Mastigophora and as cilia by (*)<* the pseudopodia (ps);/, flagel- 
.1 i j , M lum ; pd, pellicle ; B, flagellar reser- 

those who regard it as a family of voir. x eso. (After Goidschmiut.) 
Infusoria. Since the discovery that 

the equatorial groove of the Dinoflagellata (p. 182) is not ciliated, it 
is usually regarded as a character of the class that true cilia do not 
occur ; and if the vibratile processes of the Polymastigina are true 
flagella, the only exception to this is to be found in the aberrant 
genera Pteridomonas, Maupasia, and Monomastix (pp. 164 and 170). 
As a rule, there seems to be no connection between the base of 
the flagellum and the nucleus, but such a connection can be traced 



cst. --, 


in the genera Mastigamoeba and Mastigina, recalling the relation of 
the axial filament to the nucleus in certain Heliozoa (p. 23). 

At the base of the axial filament there is sometimes found a 
minute granule, with peculiar staining properties, known as the 
blepharoblast (Fig. 2, b), and closely associated with this there is 
in the Trypanosomata l a small detached 
portion of the nucleus known as the "kineto- 

At the base of the flagellum there is often 
found a special vacuole into which the con- 
tractile vacuoles may or may not open (Figs. 
1 and 2). This is the flagellar reservoir. 
In some forms (Trichomonas and Trypanoso- 
mata) a delicate undulating membrane is 
found at one side of the flagellum (Fig. 2, 
p. 195). 

Besides the flagellate movements there are 
two other important ways by which locomotion 
can be effected by certain species, namely, by 
amoeboid and by so-called metabolic or euglenoid 
changes of shape, the former resulting in the 
protrusion of pseudopodia, and the latter 
involving alternate protraction and contraction 
of the body, as may be observed in many 
worms (Fig. 5 (28)). 

The possibility of executing amoeboid and 
ture of Copromonas. b, metabolic movements depends largely upon 

blepharoblast; c.p, cyto- . J ? 

pharynx;, cytostome ; the nature of the integument or pellicle which 
/I,"' flageiuTm^ 6 /., aC food- protects the protoplast from the surrounding 

vacuoles; N, nucleus; R, fl,-,;/) rnpHium 
flagellar reservoir. (After r lln - 

Dobeii.) There are three principal kinds of integu- 

ment, with many degrees of differentiation : 

1. Periplast. This is an integral portion of the protoplast, from 
which it is never separated and with which it divides. In naked 
cells, such as Mastigamoeba, it appears as a simple ectoplasm covered 
by a very thin pellicle (Fig. I, pel), or as an alveolar layer of proto- 
plasm (Multidlia). In most cases there is a more or less well- 
defined pellicle or plasmatic membrane, which may be distinguished 
under the name of proteid-membrane. This achieves its highest 
development in the Euglenoidea, where it often presents a spirally 
striated structure and resists decomposition (Fig. 5 (16, 17)). 

2. Perisarc. The perisarc does not, as a rule, form an integral 
part of the protoplast, and does not usually divide with it, so that 
after the division of the protoplast one of the fission-products issues 

1 For a discussion of the relations of these structures compare Dobell (3), 
Minchin (13), Moore (14), Hartman and von Prowazek (5). 

Fio. 2. 
Diagram of the struc- 


from the perisarc as a naked cell. The protoplast is never com- 
pletely adherent to its perisarc, but is capable of more or less 
independent movement within it, and recedes from it upon the 
formation of the resting-stage, and also in consequence of plasmo- 
lysis. Its chemical composition is based upon a gelatinous substance 
of carbohydrate nature, and in Dinobryon Klebs has found that the 
perisarc gives the typical cellulose reaction. 

The periplast is always present in Lissoflagellates, but the 
perisarc is a secondary formation secreted by the protoplast through 
the periplast, and may or may not be present. 

The perisarc may occur as a capsule closely investing the cell 
with an apical opening for the flagellum, as in Chrysococcus and 
Trachelomonas. In the Chrysomonadine genera Synura, Mallomonas, 
Hymenomonas, and Microglena the protoplast is closely adherent to 
the perisarc, which here tends in the direction of a true cell-wall 
and is called a cuticle. In Hymenomonas by exception the perisarc 
divides with the cell. 

The most familiar form in which the perisarc is developed is 
that of a cupule, as in the calyptoblastic Hydroids. Well-known 
examples of cupule-formation are presented by the genera Bicosoeca, 
Poteriodendron, Salpingoeca (Fig. 7 (6, 7)), Dinobryon, etc. Some genera 
secrete a stalk only, Avithout a cupule, of which AntJwphysa and 
CephalotJwmnion are among the best-known examples. 

3. 'Cell- Wall. This stands in intimate relation with the proto- 
plast, as in Algae and higher plants, so that the cell-body has no 
independent movement, apart from the automatic streaming of 
granules. The cell-wall may (Dinoflagellata) or may not (Volvo- 
caceae and Coccolithophoridae) divide with the protoplast. Its 
chemical composition resembles that of the perisarc, and in the Dino- 
flagellata consists of cellulose. In the Coccolithophoridae the cell- 
wall is built up of several shells 
composed of calcium carbonate. 

Nucleus. The nucleus of the 
Mastigophora shows many varie- 
ties of intimate structure. In .A. 
some cases the chromatin is dis- 
tributed in the form of a simple 
.chromatic network (Herpeto- 
monas), in others (Bodo, Copro- 
monas, Fig. 2) the chromatin is 

nrptjpnr in flip fnrm nf n opnfril Two sta 8 es in the mitosis of the nucleus 

mtrai of x oct n uca mmaris. A, archoplasmic body 

lump Or maSS. In Eugkna there < a > becoming elongated previous to division ; 

_.. i w > nucleus. B, the nucleus has wrapped round 

IS Within the nuclear membrane the central part of the archoplasmic body, and 

i , i the chromosomes (ch) are approaching the 

separate chromatin masses, and po ies in rows. (After CWklm.) 

in addition a substance which 

has been variously interpreted, but is usually known as the 


" nucleolar centrosome." In Noctiluca (Fig. 3) an archoplasmic 
body situated outside the membrane accompanies the nucleus and 
gives rise to the achromatic spindle of the mitotic figure. Mitotic 
division of the nucleus has been described in a large number of 
cases taken from all the principal divisions of the group, but it v is 
certain that in some cases nuclear division occurs by amitosis 
(Copromonas and others, Dobell [3]). Nuclear reduction in the for- 
mation of the gametes has been observed in some cases (Trichomonas, 
Bodo, Hexamitus, Copromonas, and others). 

Notwithstanding the great variety of structure and mode of 
division of the nuclei in the Mastigophora, there is no evidence that 
in any case a division of the nuclear substance takes place into a 
somatic nucleus and sexual nucleus, comparable with the mega- 
nucleus and micro-nucleus of the Infusoria (Heterokaryota). The 
separation of the kineto-nucleus from the main nucleus in the 
Trypanosomata may suggest that in this case there is a delegation 
of special functions in connection with the flagellum to a detached 
portion of the nucleus ; but apart from this all the Mastigophora 
are in the strictest sense Homokaryota (Hickson). 

The life -history of the organisms comprised by the class 
Mastigophora shows so many varieties that no general principles 
can be laid down in this place. The life-histories of several forms 
are described in the account given of the various subdivisions of 
the group. The great advance in our knowledge of these forms 
that has been made during the past few years suggests that a 
process of gametogenesis followed by conjugation of the gametes 
occurs in the life-histories of all the orders. 

The Mastigophora are an important component of the micro- 
plankton of oceanic and lacustrine waters. The Dinoflagellata 
together with the Algae of the natural order Bacillariaceae, to which 
the former appear to be more or less closely related, are said to 
constitute the bulk of the primary food-supply (Urnahrung) of the 
sea [Schiitt], 

It is customary, in the more recent treatises, to employ the 
term Flagellata in a restricted sense, equivalent to the Lissoflagellata 
of Lankester, with the inclusion of the Choanoflagellata. In this 
sense also the term Euflagellata has been employed, and the 
flagellate members of the freshwater plankton comprise Euflagellate, 
Dinoflagellate, and Phytoflagellate l forms. The marine plankton 
comprises in addition the Cystoflagellata and the Coccolitho- 

It is in order to avoid possible confusion that the term Mastigo- 
phora, introduced by Diesing in 1866, is employed to designate the 
entire group of flagellate organisms. 

1 Sometimes the Phytoflagellata are comprehended within the Euflagellata, but 
this tends to misapprehension. 


The six sub-classes of Mastigophora may be tabulated as 
follows : 

Sub-Class 1. Lissoflagellata ) -,-, a ,, , 

, > Luflasjellata. 

2. Choanoflagellata j 

3. Phytoflagellata (Volvocaceae). 

4. Dinoflagellata (Peridiniales). 

,, 5. Cystoflagellata. 

,, 6. Silicoflagellata. 

The Euflagellata are defined as Protozoa which possess a sharply 
defined, uninuclear sarcode, whose periplast is either a simple 
ectoplasm or a definite pellicle. During the greater portion of 
their life they are in motion, or at least capable of motion. They 
have a definite anterior end, from which one, two, or many flagella 
arise, and they possess one contractile vacuole or several. Repro- 
duction takes place by simple longitudinal fission, 1 generally in the 
flagellate condition, sometimes in a resting condition. It seems 
probable that most of the Euflagellata are capable of forming 
resistent cysts, usually called sporocysts. 

The occurrence of a process of conjugation was asserted by 
Dallinger and Drysdale and others of the earlier observers, but 
some doubt was thrown upon the accuracy of these statements by 
Biitschli and Senn. In recent years, however, the formation of 
definite gametes and a process of conjugation have been proved 
to occur in Mastigella by Goldschmidt (4), in Pseudospora by 
Kobertson (18), in Monas and Bodo by von Prowazek (16), in 
Copromas by Dobell (3), and in Trypanosoma and other forms by 
Schaudinn (19). There seems to be little doubt, therefore, that 
conjugation is a normal process in the life-history of all the 


The members of this sub-class are distinguished from the other 
Euflagellata by the absence of a collar. The sub -class is divided 
into the three orders : 

1. Monadidea. 

2. Euglenoidea. 

3. Chromomonadidea. 

ORDER 1. Monadidea, Biitschli. 

The Monadidea comprise the least differentiated forms of 
Mastigophora, and include genera that exhibit affinities with the 
Proteomyxa (Multicilia, Pseudospora, p. 8), with the Lobosa (Rhizo- 

1 Cases of true transverse fission are very rare among the Lisso- and Choano- 
flagellates ; e.g. Oxyrrhis, Stylochrysalis, Phalansterium. 



mastigoda), and possibly also with the Heliozoa (Dimorpha). They 
are colourless Flagellata with one to an indefinite number of flagella, 
a simple vacuole system, and usually a single nucleus. Their 
nutrition may be holozoic, parasitic, or saprophytic, but probably 
never holophytic. 


Solid foodtmay be ingested at all points in an amoeboid fashion. 
StrB-TRiBE 1. HOLOMASTIGODA, Lauterborn. With polyaxonic body, 
flagella scattered all over the surface, pseudopodial ingestion of food, loco- 
motion rotatory, defaecation at all points. 

Multicilia, Cienkowski ; M. marina, Cienk., with one nucleus ; M. 
lacustris, Lauterborn, plurinuclear, the only instance of the kind among 
Mastigophora. The genus Grassia, Fisch., closely allied to Multicilia, is 
found in the alimentary canal of the frog and in the blood of Hyla. 

SUB-TRIBE 2. KHIZOMASTIGODA, F. E.Schultze. With one or two flagella, 
natant and amoeboid or heliozooid phases. The flagella persist through 
the amoeboid or heliozooid phase. The monomastigote and dimastigote 
genera present a parallel series, and in addition there is an aberrant genus. 
Pteridomonas, Penard, in which there is a circlet of 8-12 cilia, which can 
be rolled inwards like a watch-spring and then bent outwards, exerting a 
jerking action by which the animal hops backwards. 
These cilia surround the base of the single main 

In the genus Mastigamoeba the flagellum arises 
directly from the nucleus. The genus Mastigina 
(Frenzel) is closely related to Mastigamoeba, but the 
body is covered with a thick pellicle. The position 
of Mastigella, Frenzel (Fig. 4), is more difficult to 
determine, as there may be one or more flagella 
which are quite independent of the nucleus. In 
Mastigamoeba schulzei (Frenzel) and Mastigina setosa 
(Goldschmidt) the body is thickly beset with long 
rigid bristles which have the general appearance 
of cilia, but seem to have the same nature as the 
adhesive granules (Klebkdrner) with which the 
pellicle and superficial ectoplasm of several species 
of the three genera are provided. It is possible 
that they are of the same nature as the spicules 
of the ectoplasm found in several of the Lobosa 
Mastigella vitrea, Gold- (Trichosphaerium, etc.) and some of the Heliozoa 

schmidt. OneoftheRhizo- ) 2 ' ~n ao\ 

mastigoda. Active form. (Heterophrys (ct. pp. 23, 68). 

c., contractile vacuole ; 

/. portions of filamentous m, i-r v i. r -nr , 77 , i 

algae ingested as food ; fl, Ine liie-nistory of Mastigella vitnna has 
ScTmidto 250 - (After recently been fully investigated by Gold- 
schmidt (4). During the vegetative life of 
this animal a series of binary fissions occur which are preceded 
by a withdrawal of the pseudopodia and flagellum and a mitotic 

Fio. 4. 


division of the nucleus. The number of chromosomes seen in these 
mitotic divisions is about 40, and there are no centrosomata at 
the poles of the spindle. The sexual reproduction is preceded 
by the formation of mega- and microgametocytes. In the early 
stages the gametocytes cannot be distinguished from the ordinary 
vegetative individuals except as regards the microscopic character 
of the nuclei. A number of minute granules of chromatin 
(chromidia or sporetia of Goldschmidt) are extruded from the- 
nucleus, increase in number and size, and give rise to the nuclei 
of the numerous gametes. The cytoplasm of the gametes is 
formed by a differentiation of clear protoplasm around each 
nucleus. In the case of the formation of the megagametes at least 
one mitotic division of the nucleus occurs, which has been inter- 
preted to be a polar division. A similar polar division of the 
nucleus probably takes place also in the formation of the micro- 
gametes. The elements of these nuclei are so small that it has 
not been proved that a definite reduction in the number of the 
chromosomes occurs. In both kinds of gametocytes an encystment 
accompanied by withdrawal of the pseudopodia and flagella occurs, 
but the microgametocyte encysts sooner than the megagametocyte. 
The gametes escape from the gametocytes and conjugate to form 
a zygote. The megagametes are about 3-6 /* in diameter and 
are provided with a single flagellum 15-18 /A in length. The micro- 
gametes are 2-8 /* in diameter and are also provided with a 
flagellum. The zygote is a minute active monad, which divides 
several times by simple fission and then grows and assumes the 
general characters of the genus. 

The principal genera are : Amoeboid and monomastigote : Mastiga- 
moeba, Schulze ; Mastigella, Frenzel ; Mastigina, Frenzel. Amoeboid and 
dimastigote : Cercobodo, Kent = Dimastigamoeba, Blochmann, and some of 
the species attributed to the genus Cercomonas (Fig. 5 (32, 33)). Heliozooid 
and monomastigote : Actinomonas, Kent. Heliozooid and dimastigote : 
Dimorpha, Gruber. 

TRIBE 2. PROTOMASTIGINA (sensu stricto). 

Solid food is ingested at a fixed point near the base of the flagellum. 

SUB-TRIBE 1. MoxoMASTiGODA. 1 A. Flagellum directed forwards, 
a. Oicomonas, Kent (Fig. 5 (29, 30, 31)). Ingestion of food at base of 
flagellum by means of a protuberant vacuole (vacuolar ingestion) which 
subsequently migrates to the posterior end. /3. Leptomonas, Kent. Rod- 
shaped or fusiform, parasitic in intestine of insects. B. Flagellum 
directed backwards, a. Ancyromonas, Kent. The single flagellum arises 
at anterior end, but is bent backwards and serves as an anchor or 

1 Tdis sub-tribe comprises the Cercomonadina of Saville Kent or the Oicomona- 
daceae of Senn. From the work of Klebs and others it seems necessary to reject 
the genus Cercomonas, since the confusion surrounding it cannot lie lightened. 


gubernaculum as in Bodo. Marine. (3. Phyllomonas, Klebs. A triangular, 
contorted, foliaceous monad with the flagellar pole directed backwards 
in locomotion ; the flagellum acts therefore as a pulsellum. Stagnant 
water. C. Sessile, calyptoblastic genera, a. Codonoeca, Clark, constructs 
a pedunculate, ribbed, colourless theca in which it resides freely. 
Freshwater and marine. (3. Platytheca, Stein, constructs a membranous 
encrusting theca. 

The Family TRYPANOMORPHIDAE, containing the single genus Try- 
panomorpha, Woodcock, belongs to this sub-tribe. A full description of 
this form is given in Section G, p. 193. 

Fio. 5.' 

1, Chlamydomonas pidvisculus, Ehrb. ; one of the Phytoflagellata ; free-swimming indivi- 
dual ; a, nucleus ; bb, contractile vacuoles ; c, pyrenoid ; d, cellulose investment ; e, stigma 
(eye-spot). 2, resting-stage of the same with fourfold division of the cell -con tents ; 
letters a> before. 3, a cyst that has been formed by the conjugation of gametes and is now 
liberating a large number of minute biflagellate zooids. 4, Synerypta volvox, Ehrb. ; one of the 
Chrysomonadina. A colony enclosed by a mucilaginous test(c). a, stigma ; fr, vacuole. 5,Uroglen 
volvox, Ehrb. ; one of the Chrysomonadina. Half of a large colony. 6, Chlorogoniiim euchlorum, 
Ehrb. ; one of the Phytoflagellata ; a, nucleus ; b, contractile vacuoles ; c, pyrenoids ; (?) d, eye- 
spot. 7, the same species, showing conjugation of the gametes. 8, a colony of Dinobryon sertularia, 
Ehrb. ; one of the Chrysomonadina loricata, x 200. 9, Sphaerella pal u stria, Girod ( Haemato- 
coccus fxilustris) ; one of the Chlainydomonudina ; ordinary individual with widely separated 
test, to which it is attached by delicate strands of protoplasm, not shown in the figure ; 

a, nucleus ; b, contractile vacuole ; c, pyrenoid. 10, dividing resting-stage of the same. 11, a 
gamete of the same. 12, Phalansterium consociatum, Cienk. ; one of the Choanoflagellata, x 325. 
Disk-like colony. 13, Euglena virulis, Ehrb. ; one of the Euglenina, x 300 ; , pigment spot : 

b, flagellar reservoir; c, paramylum granules; <l, chromatophores. 14, Gonium pectorale, 
O. F. M. ; one of the Volvocina ; colony seen from the flat side, x 300 ; a, nucleus ; b, contractile 
vacuole ; c, pyrenoid. 15, Dinobryon sertularia, Ehrb. ; one of the Chrysomonadina loricata : 

a, nucleus ; b, contractile vacuole ; c, paramylum, (?) nucleus ; d, free colourless flagellates 
probably not belonging to Dinobryon, ; e, stigma ; /, chromatophores. 16, Paranema tricho- 
phorum, Ehrb. ; one of the Paranemina, x!40; a, nucleus ; 6, contractile vacuoles ; c, pharyn- 
geal apparatus; </, mouth. 17, anterior end of Euglena acus, Ehrb., in profile ; a, mouth : 

b, contractile vacuoles ; c, pharynx ; d, eye-spot ; e, paramylum bodies ; /, chromatophores. 
18, part of the surface of Volvox globator, L., showing intercellular connective fibrils; a, 
nucleus; b, contractile vacuole; c, pyrenoid. 19, two antherozooids (= microgametes) of 
Volvox globator. 20, ripe asexually produced daughter individual of Volvox minor, Stein, still 
enclosed in the cyst of the parthenogonidium ; a, young parthenogonidia. 21 and 22, 
Undulina ranarum, E. R. L. (see Fig. 1, p. 194). 23-26, reproduction of Bodo caudatus, Duj. ; 
one of the Heteromastigoda, according to Dallinger and Drysdale. 23, fusion of several indi- 
viduals (plasmodium). 24, encysted fusion-product dividing into four. 25, later into eight. 
26, cyst filled with swarm-spores. 27, Astasia tenax, O. F. M. ; one of the Astasiina, x 440. 
Individual with two flagella and strongly contracting hinder end of the body ; o, nucleus ; 6, 
flagellar reservoir. 28, the same devoid of flagella. 20, Oieomonas termo, Ehrb. ; one of the 
Protomastigina, x 440 ; , nucleus ; b, contractile vacuole ; c, food-inge>ting vacuole ; d, 
food-particle. 30, the food-particle has now been ingested by the vacuole. 31, Oieomonas 
mutahilis, Kent, with adherent stalk ; ., nucleus ; 6, contractile vacuole ; c, food-particle in food- 
vacuole. 32, 33, Cereobodo (Cercomonas) crassicauda, Duj., showing two conditions of the 
pseudopodium - producing tail ; a, nucleus ; b, contractile vacuoles ; e, mouth. (After 
Lankester and various authors.) 

SUB-TRIBE 2. PARAMASTIGODA. Solitary or colonial forms with one 
long flagellum and one (rarely two) short accessory flagellum near its 
base ; vacuolar digestion at the anterior end. A. Solitary genera. 
JV/onas, Stein ; Sterromonas, Kent ; Physomonas, Kent. Freshwater. 
B. Colonial genera. Cephalothamnium, Stein ; Anthophysa, Bory (Fig. 
7 (12, 13)). Freshwater. 

SUB-TRIBE 3. HETEROMASTIGODA. Solitary, colonial, free or attached 
forms with at least two flagella of different kinds, of which one is 
directed forwards and another is directed backwards, acting as a 
gubernaculum or steering flagellum in the free forms or as a stalk of 
attachment in the fixed forms. A. Free solitary and naked genera (Bodo- 
nina, Biitschli) ; Bodo (Fig. 7 (10)), Ehrenberg freshwater and marine ; 


Pleuromonas, Perty ; Phyllomitus, Stein ; Colponema, Stein ; Rhynchomonas, 
Klebs ; Oxyrrhis (Fig. 10 (2)), Duj. marine. Bodo can execute character- 
istic jumping movements by means of the gubernaculum. It captures 
its food (bacteria and infusoria) and sucks out the protoplasmic contents 
by means of a rostral process (rostral ingestion). According to Dallinger 
and Drysdale a process of plasmodium- formation occurs in this genii?, 
followed by encystment and subsequent division of the protoplasmic 
contents into numerous swarm-spores (Fig. 5 (23-26)). In Oxyrrhis there 
is a large oral funnel and a rudimentary pharynx similar to that of the 
Euglenoidea. This genus is said to divide transversely instead of 
longitudinally as in all other Heteromastigoda. The genus Costia 
(Leclerq) with three flagella, reposing in a groove when at rest, may 
belong to this sub-tribe (see p. 157). B. Sedentary and usually colonial 
forms, protected by a cup-shaped or closed theca and attached to the 
base of it by the gubernaculum. At the anterior extremity there is a 
plate-like expansion of the ectoplasm (the peristome). (Bikoecina, Stein) ; 
Bicosoeca, Clark, solitary or in rosettes ; (B. socialis, Lauterborn). 
Peristome thin and membranous. Freshwater and marine. Poterio- 
dendron, Stein, fixed, " dinobryoid " association of stalked thecate 
individuals ; peristome thick, proboscis-like. 

The Bikoecina appear to suggest a transition from the Lissoflagellata 
to the Choanoflagellata in virtue of their peristome, which is perhaps 
comparable to the collar. 

The Family TRYPANOSOMATIDAE, containing the blood-parasites Try- 
panophis, Trypanoplasma, and Trypanosoma, belong to this sub-tribe. 
The family is fully described in Section G, p. 193. 

SUB-TRIBE 4. ISOMASTIGODA. Monaxonic body with two equal 
flagella at the anterior end. A. Solitary (Amphimonadina). Amphimonas, 
Duj. ; Streptomonas, Klebs ; Diplomita, Kent. Freshwater. B. Colonial 
(Spongomonadina). Numerous individuals united "in a common jelly 
or in branched gelatinous tubes, the end of each of which is inhabited by 
a single and distinct individual." l Spongomonas, Stein ; Cladomonas, 
Stein ; Rhipidodendron, Stein. Diplomita (Kent) is now regarded as an 
individual of Spongomonas living isolated in the theca of a Bicosoeca. All 

An interesting Protozoon which is known by the name of 
Pseudospora volvocis, Cienkowski, and was placed by Biitschli in the 
tribe Isomastigoda, is found parasitic upon Volwx. According to 
Robertson (18), it has three forms, each from 12 to 30 /x in diameter. 
A, an amoeboid form ; B, a pear-shaped flagellate form, with two 
flagella at one end ; C, a spherical Actinophrys-like form. In each of 
these forms there is a single definite nucleus containing a centrally 
placed karyosome surrounded by clear nucleoplasm. The amoeboid 
form feeds by ingesting individuals of the Volwx colony, and it 
gives rise to the flagellate form, which swims away and attacks 
another colony. Reproduction of the amoeboid form occurs 

1 Lankester, E. R., Enci/. Brit., 9th Ed., Art. "Protozoa." 


accompanied by a definite mitotic division of the nucleus. 
Alternation of the amoeboid and flagellate forms with reproduction 
by fission continues for about eighteen days, and then gameto- 
genesis sets in. The gametes are minute (1-2 p, in length) uni- 
fiagellate organisms, and soon after their escape they conjugate in 
pairs to form the zygotes. Gametogenesis occurs in the amoeboid 
form, without encystment or withdrawal of the pseudopodia, and the 
number of gametes formed by a single individual may exceed one 
hundred. After a time the zygotes withdraw their flagella, assume 
a spherical shape, and then creep into a Volwx individual. 
Gametogenesis may also occur in the radial form, but it has not 
been observed in the flagellate form. 

It does not seem to be certain that the species described belongs 
to the same genus as others that have been attributed to Pseudospora 
(see p. 8), but the description of its life-history given by Miss 
Robertson proves that it is not a Proteomyxan, but is correctly 
placed with the Mastigophora. 


With more than two flagella (exclusive of Multicilia). 

SOB-TRIBE 1. TRIMASTIGINA. Three flagella. Trimastix, Kent ; 
Dallingeria, Kent ; Elvirea, Paroiia. Costia necatrix, Henneguy, is a 
flagellate ectoparasite of the trout which cannot live in infusions, but 
requires very pure water. It is the only flagellate ectoparasite known 
which cannot live apart from its host. It penetrates into the epidermis 
of the fry, frequently causing a mortal disease. The adult fishes are 
immune, being protected from the parasite by their scales. 

SUB-TRIBE 2. MoxosiOMATiNA. 1 Four (rarely six) flagella, one 
mouth-spot or oral groove, unilateral, asymmetrical. Tetramitus, Perty 
(Fig. 7 (14)); Collodictyon,C&i'teT; Trichomonas, Donne" ; Trichomastix^loch- 
mann ; Monocercomonas, Grassi ; Megastoma, Grassi. Megastoma entericum, 
parasitic in man and domestic animals, is regarded as intermediate 
between the Tetramitina and the Distomatina (Klebs), having a uni- 
lateral mouth as in Tetramitus and sextuple flagella as in Hexamitus. 
Trichomonas, Donne. T. intestinalis is found in the intestine of mice. 
" It is pear-shaped with three flagella springing from the blunt end, and 
an undulating membrane with a thickened border passing in a spiral 
manner round the body and terminating in a free flagellum " (Wenyon). 

SOB-TRIBE 3. DISTOMATINA, Klebs, 1892. Body bilateral but not 
symmetrical, since the two mouth-spots (oral grooves) are placed on 
opposite surfaces of the body ; flagella arranged in pairs. Principally 
found in stagnant water. Gyromonas, Seligo, 4 flagella ; Trigonomonas, 
Klebs, 6 flagella ; Trepmnonas, Duj., 8 flagella ; Hexamitus, Duj. (Fig. 7 
(5)), and Urophagus, Klebs, with 6 or 8 flagella, of which two or three 
pairs are anterior and the fourth pair are gubernacula (Schleppgeisseln). 
The two last-named genera are, alone among Flagellata, characterised by 

1 Including the Tetramitina, with a wider significance. 


forming, as products of metabolism, glycogen-like bodies (Klebs). H. 
muris is found in the intestine of mice (Wenyon). Lamblia intestinalis 
is found in the intestines of various mammals, and is not infrequently 
parasitic in man. It is not thought to be pathogenic. Spironema, Klebs. 
Polymastigote ; flagella arising in pairs at the margins of the spiral 

SDB-TRIBE 4. LOPHOMONADINA, exclusively parasitic in the rectum of 
insects. This sub-tribe is regarded by some authors as having closer 
affinities with the Ciliata. It has already been described under the 
heading Family Trichonymphidae in Fasc. II. p. 417 of this Treatise. 
The genus Maupasia (Schewiakoff) has the anterior part of the body 
covered with cilia, but at the posterior end it bears a long flagellum. By 
some authors it is regarded as a Polymastigine flagellate, but its affinities 
seem to be with the Ciliata. Freshwater. Hawaii. Monomastix, Roux, is 
another genus with a polar flagellum and cilia in longitudinal rows. 
There are said to be two meganuclei and two micronuclei. This genus 
should also be included in the Ciliata. 

ORDER 2. Euglenoidea. 

The second order of Lissoflagellata comprises the most highly 
organised members of the sub-class. This high degree of special- 
isation is indicated by the structure of the pharyngeal armature of 
the tribe Peranemina, which consists of two converging rods, which 
can be protruded from the base of the oral funnel. 

With regard to the nutrition of Mastigophora as a class, to 
which allusion has already been made, it is necessary, even from a 
purely systematic standpoint, to consider (1) the nature of the 
food ; (2) the mechanism of ingestion ; (3) the products of meta- 
bolism. In holozoic nutrition the food consists of bacteria, other 
monads, swarm-spores of Algae, starch, and the like. The modes 
of ingestion by which these food-bodies are conveyed into the pro- 
toplast of the feeding organism are of five principal kinds, namely, 
pseudopodial ingestion (Pantostomatina) ; vacuolar ingestion (Mono- 
mastigoda, Paramastigoda, Isomastigoda, Choanoflagellata) ; rostral 
or suctorial ingestion (Heteromastigoda) ; stomatic ingestion, by 
which the food sinks into the protoplasm through one (Monostoma- 
tina) or two (Distomatina) points of least resistance situated in one 
or two depressions (oral grooves) below the insertion of the flagella ; 
pharyngeal ingestion (Peranemina). 

Not only does the mode of feeding distinguish the Peranemina 
from all other Flagellata, but they are further distinguished by 
their well-marked, spirally striated periplast or cuticula. In the 
Euglenoidea the periplast is generally a striated, resistent proteid- 

The vacuole-system of the Euglenoidea consists of a non-con- 
tractile or feebly contractile reservoir provided with an excurrent 


canal opening at the apex of the cell, and one or many accessory 
contractile vacuoles discharging into the reservoir (Fig. 5(17)). A 
similar kind of compound vacuole-system is also met with among 
the Peridiniales (Fig. 12). 

The products of metabolism which occur in the Euglenoidea 
consist of fatty oil and paramylum, a substance allied to starch, but 
not giving the typical starch-reaction. It is interesting to note that 
the saprophytic Euglenoids of the tribe Astasiina, which are destitute 
of chlorophyll, none the less produce paramylum. 

The Euglenoidea include holozoic, holophytic, saprophytic, and 
mixotrophic species, and one of the most characteristic properties 
which they have in common is the formation of paramylum as the 
principal product of metabolism. 

This order presents a series of forms analogous to the Mona- 
didea in regard to the distribution of the flagella : monomastigote 
forms (JEuglena, Peranema, dstasin) ; paramastigote (Distigma, 
Sphenomonas, Tropidoscyphus) ; isomastigote (Eutreptia) ; and, finally, 
heteromastigote forms (Heteronema, Dinema, Anisowma). 

The Euglenoidea are divisible into two sections and three tribes. 

A. Without special pharyngeal apparatus. 


Holophytic. A red stigma or eye-spot close to the vacuole is present, 
.iind green chromatophores. 

Euglena, Ehrb. (Fig. 5 (13, 17)) ; Colacium, Ehrb. ; Lepocinclis, Perty ; 
Trachelomonas, Ehrb. ; Eutreptia, Perty ; Ascoglena, Stein ; Cryptoglena, 
Ehrb. Trachelomonas is sometimes found in the sea ; the others are 
freshwater forms. 


Saprophytic, without chlorophyll. Astasia (Fig. 5 (27, 28)), Duj. ; 
Distigma, Ehrb. ; Sphenomonas, Stein ; Menoidium, Perty ; Rhabdomona.*, 
Fresenius ; Atractonema, Stein. All freshwater forms. 

B. With special pharyngeal apparatus. 



a. With one flagelluin. Paranema (Fig. 5 (16)), Duj. ; Euglenopsis, 
Klebs ; Urceolus, Meresch. ; Petalomonas, Stein ; Scytomonas, Stein. All 
found in fresh water, but Euglenopsis flourishes in vegetable infusions. 
Copromonas, Dobell (3), parasitic in intestine of frogs. 

(3. With two flagella. Heteronema, Duj. ; freshwater and marine. 
Dinema, Perty ; stagnant freshwater. Zygoselrnis, Duj. ; freshwater. Tropi- 
doscyphus, Stein ; freshwater; Anisonema, Duj. ; freshwater Entosiphon, 
Duj. ; marine and freshwater. 


One of the commonest of the Euglenoidea is Euglena viridis, a 
species which is frequently found in shallow ditches and puddles, 
giving the water a green tint or forming a green scum on its- 
surface. The free -swimming individuals are about O'l mm. in 
length, provided with a single flagellum arising just in front of a 
short funnel-shaped cytostome at the pointed anterior end of the 
body. Opening into the cytostome funnel there is a small reservoir, 
which itself receives the fluids discharged by a system of minute 
contractile vacuoles. The chlorophyll is present in the form of 
numerous minute chloroplasts, and the paramylum in the form of 
many minute plates. At the base of the flagellum there is a red 
eye -spot composed of numerous granules of " haematochrome." 
There is a single nucleus. An important phase in the life-history 
is the resting stage. The individuals swarm to the surface of the 
water, where they form the green scum. Each individual in the 
scum loses its flagellum, and, secreting a gelatinous substance 
which joins with that of its neighbour's to form a continuous jelly,, 

Division of the nucleus and cell-substance takes place during 
the resting stage at night. The mi to tic changes commence about 
two hours after dark and are completed in five hours. The 
nucleus has in the resting stage a centrally placed " nucleolo- 
centrosome." This becomes dumb-bell-shaped and then elongates- 
in mitosis. The chromosomes become parallel to this body, and 
eventually form an equatorial ring round it. In this position they 
undergo longitudinal splitting (Keuten). 

Euglena undergoes several successive divisions under the same 
cyst-membrane, forming quadrants, octants, etc., but all result from 
successive longitudinal division, unlike the ciliate infusorian Colpoda,. 
which produces similar clusters resulting from successive cross- 
division. Again, in the Volvocines the clusters arise by alternate 
longitudinal and transverse division (Klebs). 

Thus, in the case of Euglena and Copromonas, division takes- 
place after the loss or withdrawal of the flagellum, but in the allied 
Astasiina division takes place during the motile phase. 

Euglena gracilis occurs in both green and colourless conditions, 
so that, employing Pfeffer's terminology, it may be at one time 
autotrophic (holophytic), at another time heterotrophic (sapro- 
phytic), the two conditions being connected by a mixotrophic 

An important contribution to the life-history of the Euglenoidea 
has recently been made by Dobell (3). In Copromonas subtilis, from 
the intestine of the common frog and toad, reproduction is effected 
by simple longitudinal fission accompanied by amitotic division of 
the nucleus. After a period of from two to six days a considerable 
number of individuals are found to be conjugating. All the 


individuals appear to be facultative gametes and there is no sexual 
differentiation. During the conjugation the nucleus of each of the 
conjugants divides at least once, one of the daughter nuclei thus 
produced, being a polar nucleus, degenerates in the cytoplasm and 
is lost. The remaining nucleus of each conjugant fuses with its 
fellow to form the nucleus of the zygote. It should be stated that 
after the first division of the nuclei of the conjugants small granules 
of chromatin are protruded from the central chromatin mass and 
are lost in the cytoplasm (heteropolar division). The zygote 
behaves exactly like an ordinary individual and divides soon after 
it is formed by longitudinal fission in the ordinary manner. 

ORDER 3. Chrcmomonadidea. 

This is the first of the groups of Mastigophora that are regarded 
by many authors as belonging to the vegetable kingdom ; for, 
although there is an active free- swimming stage of life, the method 
of nutrition appears to be in all cases holophytic. In the Chloro- 
monadina, which may be regarded as in many respects intermediate 
between this order and the other Lissoflagellata, there is a funnel- 
shaped depression at the base of the flagellum ; but this does not 
serve the purposes of a mouth, but is an excretory duct of the 
contractile vacuole reservoir. In the other tribes of the order 
even this vestige of the Lissoflagellate mouth is lost. The Chloro- 
monadina also resemble the Euglenoids in having the chlorophyll 
scattered through the endoplasm in minute chloroplasts. No 
process of conjugation has yet been observed in this order. Among 
the Chrysomonadina, Chrysamoeba has the ordinary form of a 
flagellate organism when it is actively swimming, but when it 
comes to rest it protrudes delicate radiating pseudopodia and 
resembles a Mastigamoeba. 

Chromulina rosanoffi, according to Woronin (23), forms a scum of 
encysted individuals at the surface of ponds in Finland. This 
gives rise to the flagellate swarm-spores which after a time penetrate 
the cells of Spirogyra and again encyst. In Dinobryon the indi- 
viduals are attached to the base of an open receptacle. They 
usually occur in dense spreading free-swimming colonies (Fig. 5 (8)). 
Reproduction is by fission or by the formation of spherical cysts 
which escape from the receptacle and start new Dinobryoid colonies. 
Syncrypta (Fig. 5 (4)) forms globular colonies invested by a 
mucilaginous test through which the flagella protrude. Uroglena 
also forms globular colonies, but the flagellate individuals are at the 
periphery and the centre is filled with mucilage. 

The genera comprised in this order are freshwater in habit, 
except the Coccolithophoridae, which are exclusively marine. 

The order is divided into three tribes : 



The body is naked, the periplast consisting of a smooth non-resistent 
membrane formed by a thick layer of ectoplasm, in place of the in- 
tegument of the Euglenoids. The chloroplasts are generally numerous 
and the vacuole-system is compound, resembling that of the Euglenoids. 
The product of metabolism is neither starch nor paramylum, but fatty 
oil. There is a funnel-shaped depression at the base of the flagellum 
corresponding with the cytostome, but not used for the ingestion of food. 

Genera Facuolaria, Cienkowski ; Coelomonas, Stein; Raphidomonas, 


The members of this tribe resemble the Protoinastigina, with the 
addition of chromatophores which carry a yellowish-brown pigment called 
chrysochrome, allied to diatomin. The chrysochrome-plates are usually 
two in number, placed right and left. They do not contain pyrenoida 
and do not manufacture starch. There is a red stigma (eye-spot). The 
products of metabolism are fatty oil and a refringent soluble proteid 
called leucosin (Klebs). 

Nutrition is generally holophytic ; there is no mouth ; generally two 

The tribe is divided by Klebs into three sections or sub-tribes : 


Chrysamoeba, Klebs ; Chromulina, Cienkowski ; Ochromonas, Vyssotzki ; 
Stylochrysalis, Stein. The last-named is attached to colonies of Eudorina. 


Dinobryon, Ehrenberg (Fig. 5 (8, 15)) ; Hyalobryon, Chi-ysopyxis, Ehrb.; 
Chrysococcus, Klebs ; Cyclonexis, Senn. 

The researches of Lohmann (11) have shown that the family 
Coccolithophoridae must be included in this group. 

The members of this family are extremely minute organisms, 
of which the largest species are only 25-50 p. in diameter, found in 
the plankton of the sea and characterised by the possession of 
a theca composed of minute calcareous shells which have long 
been familiar to zoologists under the names "coccoliths" and 
" rhabdoliths." 

The organism bears one flagellum or two equal flagella, a single 
nucleus, two (rarely one) large green or brown chromatophores, 
each containing a drop of a substance which appears to be oil 
(Fig. 6, D), and in many cases a vacuole situated near the base of 
the flagellum. The body is surrounded by a soft membrane which 
supports the theca of calcareous shells. The shape of the shells 
that compose the theca shows immense variety in the family. Two 



kinds have been distinguished, those that are imperforate (discoliths, 
lopadoliths, calyptroliths), and those that have a central perforation 
(Fig. 6, B) (placoliths and rhabdoliths). The significance of the per- 
foration in the placoliths and rhabdoliths is not clear, but there is 
no evidence at present that it transmits protoplasmic processes from 
the ectoplasm. 

When the theca is once formed it is never increased in size by 
the addition of new shells, but when the growth of the organism 



FIG. 6. 

To illustrate the structure of the Coccolithophoridae. A, Scyphosphaera apsteini, Lohmann,. 
X 2000. (j, a girdle of peculiar enlarged coccolitlis. B, optical vertical section of an example 
of a perforated coccolith of Coccolithrrpora Irptopora, M. and B. C, side-view of a simple collar- 
shaped imperforate coccolith of Calyptrosphaera oblonga, Lohmann. D, vertical section of 
Pontosphuera haeckelii, Loh. ; co, the sheath of coccolitlis ; ch, the two chromatophores', eacli 
containing a highly refractive globule ; /, the flagellum ; n, the nucleus. B, side-view of one 
of the coccolitlis of the same species. F, Discosphaera tubifer, M. and B. ; ch, chromatophores. 
G, trumpet -shaped projection from the coccolith of Discosphaera tubifer, x 2000. '(After 
Lohmann and Murray and Blackman.) 

requires it, the theca is cast off as a whole and a new one formed 
in its place. 

Reproduction is usually effected by simultaneous longitudinal 
fission of the theca and protoplasm, but occasionally large thecae 
are found containing two individuals, indicating that fission of the 
protoplasm may precede division of the theca or the formation of 
two thecae. 

No evidence has yet been obtained of the formation of gametes. 

The Coccolithophoridae are exclusively marine, but are found 
everywhere except in pure polar waters. They reach their greatest 
numbers at a few fathoms from the surface. 


Sub-Family SYRACOSPHAERINAE. Pontosphaera (Fig. 6, D), Scypho- 
sphaera (Fig. 6, A), Syracosphaera, and Calyptrosphaera all described by 

Sub-Family COCCOLITHOPHORINAE, Lohmann. Coccolithopora, Loh. ; 
Umbilicosphaera, Loh. ; Discosphaera, Haeck. (Fig. 6, F) ; Rhabdosphaera, 


Mallomonas, Perty ; Synura, Ehrenberg ; Syncrypta, Ehrenberg (Fig. 
5 (4)) ; Uroglena, Ehrenberg (Fig. 5 (5)) ; Microglena, Ehrenberg ; Hymeno- 
monas, Stein. 


Coloured or colourless forms with one to three green chromatophores 
or none. Nutrition is never holozoic and the product of metabolism is 
starch, as in green Algae and in Dinoflagellata. The anterior end is 
more or less obliquely truncate, usually with a deep frontal infundibulum l 
like a peristome, from the side or bottom of which the two flagella arise. 

Cryptomonas (holophytic), Ehrenberg ; Cyathomonas, Fromentel ; and 
Chilomonas (saprophytic), Ehrenberg. 

In Cryptomonas the colour of the chromatophores varies from green to 
brown and yellow ; two are dorsal and one ventral. Cyathomonas possesses 
no chloroplasts. 

Closely related to the Cryptomonadina are the Phaeocapsaceae, contain- 
ing the genera Phaeococcus, Borzi ; Phaeosphaera, West ; and Stichogloea, 
Chodat. In these forms a large number of non-flagellate cells form a 
mucilaginous investment ; but as the asexual reproduction takes place 
principally during this phase of life, they are more usually regarded as 
algae. The same may be said of the genus Hydrurus, Ag., in which the 
cells are enclosed in a tough cylindrical mucilaginous envelope. 


The Choanoflagellata are frequently regarded as constituting 
a subdivision of the Protomastigina, a proceeding which is in 
accordance with their affinities, though such is the singularity 
of their form that it seems quite as appropriate to preserve their 
independence as to merge them into a larger group. There are 
no permanently free-swimming species, all are either sessile or 
pedunculate, solitary or colonial. They can, however, quit their 
.attachment temporarily and swim about with the collar directed 
backwards. The collar may be defined as a special development 
of the peristome surrounding the single flagellum which acts as a 
pulsellum in locomotion. The collar is a contractile protoplasmic 
process comparable in some respects to an undulating membrane. 

The organism feeds by means of vacuolar ingestion, the food 

1 Flagellar fundus. See also under Dinoflagellata, p. 187. 


particles being carried down on the outer surface of the collar, at 
the base of which they sink into the body of the cell. 

Several of the genera are found both in the sea and in fresh 

There are two orders of Choanoflagellata : 

ORDER 1. Craspedomonadina, Stein. 
A. NUDA, Lankester. 

Monosiga, Kent ; Diplosiga, Frenzel (with two collars, one within the 
other) ; Hirmidium, Perty ; Codosiga, Kent (Fig. 7 (3, 4)). 

B. LORICATA, Lankester. 

Salpingoeca, Clark (Fig. 7 (1, 6, 7)); Polyoeca, Kent; Sphaeroeca, 

ORDER 2. Phalansteriina ( = Gelatinigera, Lankester). 

"The cell-units secrete a copious gelatinous investment and form 
large colonies." 

Phalansterium, Cienkowski (Fig. 5 (12)), with inconspicuous collars ; 
Proterospongia, Kent (Fig. 7 (15)), with conspicuous collars. 


The Phytoflagellata or Volvocaceae are clearly related to the 
Chromomonadidea, and some authors include this order in the sub- 
class. Now that it has been definitely ascertained that conjugation 
does occur in many of the Euflagellata, the formation of a zygote by 
the copulation of two gametes is a feature that does not distinguish 
the Phytoflagellata from the other sub-classes of the Mastigophora. 
Moreover, although in Copromonas and some other Monadidea the 
conjugating individuals cannot be distinguished from the asexual 
individuals, definite micro- and megagametes are formed in the life- 
history of Mastigella, Trypanosoma, and others. The phenomenon of 
gametogenesis therefore is not a distinguishing character of the 
sub-class. The Phytoflagellata, however, exhibit a much more 
definite approximation to a purely vegetable structure than any 
of the Euflagellata, and it may be convenient to keep them together 
for the present in a separate sub-class. 

The sub-class includes solitary and colonial forms, and the body 
of the cell-unit is enclosed by a firm cell-wall which sometimes takes 
the form of a bivalvate shell (Phacolus). In the colonial forms the 
cell -units are embedded in a gelatinous matrix. There is no 
indication of pharynx, nutrition being holophytic except in the case 
of Polytoma, which is a colourless, saprophytic Chlamydomonad. 


There is usually a single large green chloroplast enclosing one 
or more pyrenoids, and the product of metabolism is starch. The 
vacuole-system consists, as a general rule, of two alternately con- 
tracting vacuoles. There is a red stigma at or near the flagellar 
basis. There are never less than two equal flagella, rarely four as 
in Carteria and Pyramidomonas. 

The Phytoflagellata are freslnvater in habit. 

Among the organisms which are closely related to the Phytoflagellata, 
but which are regarded in this volume as being just over the border-line 
between the animal and vegetable kingdoms, we may include the families 
Pleurococcaceae, Hydrodictyaceae, Protococcaceae, and Palmellaceae. The 
genera Pleurococcus, Menegh., and Trochiscia, Kiitzing, belonging to the 
Pleurococcaceae, have a more definite cell -wall and a more pronounced 

FIG. 7. 

1, Scdpingoeea fusiformis, Kent; one of the Craspedomonadina. The protoplasmic body is 
drawn together within the goblet-shaped cell, and divided into numerous spores, x 1500. 
2, escape of the spores of the same as monomastigote swarm-spores. 3, Codosigc vmlieUntii, 
Tatem ; one of the Craspedomonadina. Adult colony formed by dichotomous growth, x 625. 

4, a single zooid of the same, x 1250. a, nucleus; b, contractile vacuole ; c, the collar. 

5, Hexam itux i/ijlutus, Duj. ; one of the Polymastigina, x 650. Normal adult showing (.) nucleus 
and (6) contractile vacuole. 6, 7, Salpingoeca ttrceolata, Kent; one of the Craspedomonadina. 
('>, with collar extended ; 7, with collar retracted within the stalked cupule. 8, Polytoma urvlln, 
Miill. ; one of the Chlamydomonadina, x 800 ; , nucleus ; 1), contractile vacuoles. P, Lopfcomowu 
Mathirum, Stein ; one of the Polymastigina. 10, Bodo lens ; one of the Heteromastigoda, x 800 ; 
K, nucleus; b, contractile vacuole; the wavy filament is a flagellum, the straight one is the 
gubernaculum. 11, TetrutiiifH* .--iili'ittits, Duj.; one of the Polymastigiiia, x 430; a, nucleus; 
ft, contractile vacuoles. 12, Anthophysu rryetans, O. F. M. ; one of the Paramastigoda, x 300. 
A typical, erect, shortly-branching colony stock with four terminal monad clusters. 13, monad 
fluster in same optical" section (x 800), showing the relation of the individual monads to the 
stem (a). 14, Tetrniiutun /.-/;, itn.t. Ferty, x 1000 ; a, nucleus; b, contractile vacuole. 15, 
Proterospongia haeckeli, Kent ; one of the Phalansteriina, x 800. A social colony of about forty 
flagellate zooids. o, nucleus ; b, contractile vacuole ; c, amoebiform zooid sunk within the 
common test ; c/, similar zooid multiplying by transverse fission ; e, normal zooids with their 
collars retracted ; /, hyaline mucilaginous common test or zoothecium ; g, individual contracted 
and dividing into minute flagellate spores (microgametes), comparable to the spermatozoa of a 
sponge. (After Lankester and various authors.) 

vegetative phase of life than SpJuierella, but in other respects are closely 
related to it. The genus Hydrodictyon, Roth, forms a net-like coenobium 
which floats at the surface of the water, and Fediastrum, Meyen, which 
is also placed in the family Hydrodictyaceae, a flat plate-like coenobium 
of cells that is protected by a thick and ornamented cell-wall. Among 
the Protococcaceae such genera as Botryococcus, Kiitzing ; Tetracoccus, 
West ; Ineffigiata, West, are probably closely related to some ancestral 
form allied to tiphaerella ; but in some of the other genera, such as 
Selenastrum, Reinsch ; Ankistrodesmus, Corda ; Dadylococcus, Nageli, in 
which the cells are elongated and spindle-shaped ; and in Archerina, 
Lankester 1 ; and Chodatella, Lemmermann, in which the cell-walls are 
provided with long, stiff, bristle-like processes, there is a more pronounced 
diversion from the Chlamydomonadine ancestry. 

The family Palmellaceae has diverged from the same ancestry by the 
development of a conspicuous envelope of mucilage, but it contains some 

1 The genera Golenklnin, Chodat, Richteriella, Lemmermann, and Phytiielivs, 

Frenzel, are probably the same as Archerina (see p. 33). 


of the most primitive of the Chlorophyceous Algae. The principal genera 
are Palmella, Lyngbye ; Palmodactylon, Nageli ; Sphaerocystis, Chodat ; 
Schizochlamys, A. Br. ; Tetraspora, Link ; Apiocystis, Nageli ; Gloeocystu, 
Nageli ; and Palmodictyon, Kiitzing. 

ORDER 1. Chlamydomonadina. 

Solitary forms in the flagellate phase. 

In Chlamydomonas, which may be taken as an example of this 
order, there are two flagella in the free-swimming stage, the body 
is enclosed in a cellulose investment, there are two small contractile 
vacuoles at the anterior end, a stigma (eye-spot), a single nucleus, 
and one or more pyrenoids. Two individuals may conjugate and 
form a zygote. The zygote encysts, the flagella being lost, and 
the protoplasmic contents divide into as many as sixty-four cells 
(Fig. 5 (3)) ; these cells escape as flagellate individuals similar in 
general characters to the gametes, but instead of conjugating they 
form a gelatinous investment, lose their flagella, and divide repeatedly 
(the " palmella- stage "). From the gelatinous investment of the 
colony that is thus formed the flagellate gametes ultimately escape. 
Reproduction may also occur by the formation of a resting cyst and 
the division of the cell-contents into two, four (Fig. 5 (2)), or eight 
cells, which escape in a form like the parent. 

The introduction into the life-history of this genus of a non- 
flagellate " palmella-stage " during which growth and reproduction 
take place has suggested that Chlamydomonas "is the phylogenetic 
starting-point of the various lines of Chlorophyceous descent" 
(Blackman and Tansley). That there is a strong resemblance 
between the swarm-spores of many Algae and flagellate forms such 
as Chlamydomonas cannot be denied, but the conclusion that all the 
green Algae are descended from a flagellate ancestry is not universally 
accepted (see West [22], p. 33). 

Sphaerella, Sommerfeldt, 1824, is probably the correct generic name 
for a very abundant organism found in rain-pools, water-butts, etc., that 
is sometimes called Haematococcus, Agardh ; Chlamydococcus, Braun ; or 
Protococcus, Huxley and Martin. The individuals may become brick-red 
owing to the presence of " Haematochromin," and give rise to the 
phenomena known as "red rain" and "red snow." The structure and 
life-history of this organism are very similar to that of Chlamydomonas. 
The infecting organism which forms the green cells in the Turbellariait 
worm Convoluta roscoffensis is, according to Keeble and Gamble (7), a 
Chlamydomonad allied to Carteria. 

The principal genera are : 

Carteria, Diesing, with four flagella ; Chlamydomonas, Ehrenberg ; 
Sphaerella, Sommerfeldt (Fig. 5 (9, 10)) ; Haematococcus, Agardh ; Polytoma, 
Ehrenberg (Fig. 7 (8)) ; Chlorogonium, Ehrenberg (Fig. 5 (6)) ; Pyramimonas, 


ORDER 2. Volvocina. 

Individuals biflagellate, arranged in colonies called "coenobia," 
of definite forms, with a gelatinous matrix. Reproduction takes 
place by the cleavage of certain individuals (cells) of the colony 
called the gonidia. There are two kinds of gonidia the partheno- 
gonidia or asexual forms, and the gametogonidia or sexual forms. 
The gametogonidia consist of the oogonidia or female gametes and 
the antherogonidia or spermatozooids. These conjugate to form 
the zygotes. 

The volvocine colony is physiologically an individual organism, 
exhibiting histological differentiation and correlated locomotor 
Activities of the constituent cells. In Eudorina the cells are 
differentiated into male and female, the male cells arising from the 
anterior quartet, the remainder becoming female. In Volvox the 
reproductive cells, both parthenogonidia and gametogonidia, arc 
limited to a few of the cells which compose the coenobium. In 
Pleodorina the parthenogonidia are confined to the posterior 
hemisphere (Fig. 9). 

Protoplasmic intercellular connections between the cells (in- 
dividuals composing the colony) only occur in the genus Volwx, 
in apparent correlation with the high degree of individuation 
attained by this form. Each cell or " coenocyte " is contained 
within its own capsule, which is separated from neighbouring 
capsules by a radial cell-wall. The sarcode is separated from the 
cell-walls by a wide space which is occupied by the gelatinous 
matrix, and protoplasmic processes radiate through the matrix and 
traverse the cell-walls (Fig. 5 (18)). 

The coenobium of Volvox is a sphere consisting of a single layer 
of cells surrounding a central cavity, and thus presents a superficial 
analogy to the blastula- stage in the embryonic development of 
Metazoa. The presence of flagella, eye- spots, and contractile 
vacuoles attest its animal properties, while the presence of 
chromatophores, pyrenoids, and starch granules proclaim its 
vegetable affinities. 

The sphere comprises two differently constituted hemispheres. 
The trophic hemisphere is that Avhich is directed forwards during 
locomotion, and the component cells are distinguished by the 
brighter development of the eye-spots. The other hemisphere is 
the generative hemisphere, in which the oogonidia, antherogonidia, 
and parthenogonidia are chiefly formed. 

Locomotion is rotatory, i.e. forward progression accompanied by 
rotation about the main axis either to the right or to the left, 
though sinistral rotation is more frequent than dextral. 

In Volvox globator, L., the average number of cells in a mature 
coenobium is 10,000, the actual numbers ranging from a minimum 



of 1500 to a maximum of 22,000. In /'. aureus, Ehrb., the number 
of cells varies from 200 to 4400. In a third species. V. tertius, 
Meyer, intercellular protoplasmic threads are only present in young 
unhatched colonies, not in the adult condition. 

The form of the coenobium varies in the different genera. 
Gonium, Miiller (Fig. 5 (14)) ; cells 4-16, arranged in a squarish plate 
with flagella upon one face only ; envelope closely adherent. Stephano- 
fphaera, Cohn ; cells 4-8, arranged in a rounded plate with flagella upon 
one face only ; envelope swollen ; oval or spherical. Eudorina, Ehrb. ; 
coenobium ellipsoidal or spherical ; cells 16-64, similar, not crowded nor 
reaching towards centre. Pandorina, Bory ; coenobium ellipsoidal or 

spherical ; cells 16-32, simi- 
lar, crowded, reaching to- 
wards centre ; outer mem- 
brane or sheath of coero- 
biuni showing characteris- 
tic concentric stratification. 
Platydorina, Kofoid (Fig. 
8) ; coenobium horseshoe- 
shaped, flat, one cell deep, 
with 3-5 prolongations of the 
gelatinous matrix at the pos- 
FIG. 8. terior end ; cells 16 or 32 ; 

Platydoniw. w.mlata, Kofoid. A plate-like Volvocine flagella upon both sides of 

colony. The two surfaces of the colony are alike. .-, , . ., ,, nlfpr. 

The aspect of the adjacent cells alternates, so that l 

the pole bearing the flagella and stignia of one 'cell natin". In side view the 

is turned in the opposite direction to that of its im- , . , , 

mediate neighbours, B, x. A, front view of the colony ; plate IS seen to be twisted 

B, side view; C, a single cell showing, /, the flagella; cli a htl v in a Ipft sniral r> at 

T, the vacnoles \ *t, the stignia ; N, the nucleus ; and sll g ntl y !1 

P, the pyrenoid. (After Kofoid.) to describe a figure of 8. 

The asexual reproduction of 

Platydorina has been observed by its discoverer (Kofoid, 1900) repeatedly 
during five years, but sexual reproduction has not been seen in this genus. 
All the cells are gonidial, each capable of dividing to form a daughter 
coenobium. The daughter colonies acquire the adult form and torsion 
before escaping from the maternal matrix, which then undergoes dis- 
integration. Pleodorina, Shaw (Fig. 9) ; coenobium ellipsoidal ; cells 32, 
arranged in 5 circles, 4 in each polar circle, 8 at the equator, and 8 
in each intervening tract. Vegetative cells always 4 at the anterior 
pole. Gonidial cells twice as large as the vegetative. 


The Dinoflagellata or Peridiniales, formerly called Cilioflagellata 
under an erroneous impression concerning the nature of the trans- 
verse flagellum, are heteromastigote forms usually possessing a 
complete cellulose membrane or cuirass which is never silicified. 
The chromatophores are predominantly brownish coloured with a 



pigment known as peridinin. Eeproduction takes place by oblique 
fission (Fig. 11) and by swarm-spores. 1 There are two flagella 
generally lodged in grooves, of which one traverses the latitude of 
the body and the other the longitude. The former is called the 
annulus or girdle and the transverse flagellum plies within it 
(Fig. 10 (3)). The longitudinal groove is the sulcus harbouring the 
longitudinal flagellum. 

As already indicated, the Dinoflagellata constitute a very 
important component of the freshwater and marine plankton, the 
same generic forms occurring in both media. Moreover, they play 
an important part in the physiology of oceanic life as a whole. 

FIG. 9. 

Pleoilorina illinoisensis, Kofoid. Colony of thirty-two cells. The four small cells at the 
.interior pole are the vegetative cells (w), the remainder are facultative parthenogonidia, 
pp. x 300. (After Kofoid.) 


There is no cuirass, but the grooves are present. The transverse 
groove may be semiannular in extent and subcentral in position, with the 
longitudinal fissure straight and nearly at right angles to it on the ventral 
side (Hemidinium, Fig. 10 (1)) ; or the transverse groove may form a com- 
plete ring subterminal in position passing into the ventral longitudinal 
fissure, the anterior or prae-annular portion being much smaller than the 
posterior and presenting the appearance of a rostrum (Amphidinium) ; again, 
the annulus may be complete and occupy approximately the equator of the 
cell, and the sulcus straight (Gymnodinium) ; finally, both annulus and 
sulcus may have a spiral twist (Spirodinium, etc.). 

1 Zederbauer (24) has described a process of the fusion of the protoplasm of two 
individuals of Ceratiitm hirundinella which he regards as conjugation, but as the 
further history of the zygote (?) has not been traced, it may be only of the nature of 
plastogamic union such as we find in the Lobosa and Heliozoa. 

1 84 


The genera thus fall into two groups : 

A. Annulus and sulcus simple, at right angles to one another, decus- 
sating at one point, from which the two flagella take their origin. 

Gymnodinium, Stein. Freshwater and marine. Hemidinium, Stein 
(Fig. 10 (1)). Freshwater. Amphidinium, Clap, and Lach. 

FIO. 10. 

1, Diagram of Hemidinium, one of the Dinoflagellata; 71, nucleus; /, flagellum of the 
transverse groove ; h, flagellum of the vertical groove. 2, diagram of Oxyrrhis, one of the 
Heteromastigoda (to compare with the preceding); n, nucleus; g, the deep fossa or pit in 
which the two flagella are affixed ; t, the origin of the flagellum, which corresponds with that of 
transverse groove of Dinoflagellata. 3, Glenodinium einctum, Ehrb., one of the Peridiniaceae ; 
a, amyloid granules ; 6, eye-spot ; c, chromatophores ; d, flagellum of the transverse groove ; 
, flagellum of the vertical groove ; v, vacuole. 4, the same seen from the hinder pole. 5, 
cuticle of Histioneis cymbalaria, iStein, from the Atlantic ; i, ventral process ; k, cuticular 
collar ; I, posterior process. 6, the same seen from the dorsal surface ; m, cephalic funnel 
(epitheca). 7, cuticle of Amphisolenin globifera, Stein, from the Atlantic, seen from the left 
side ; m, epitheca ; o, the fundus from which the sulcus proceeds to the sub-terminal annulus ; 
p, pharynx ; q, the shrunken protoplasm. 8, cuticle of Ornithocereus magnificus, Stein, from 
the Atlantic ; m, m', the epitheca ; r, r', the two large ribs of the cuticular collar ; s, the two 
rows of cuticular teeth. 9, cuticle of Ceratocorys horrida, Stein, from the Southern Ocean ; 
p, p', borders of the annulus expanded into a rim ; w, x, y, plumose spines of the left margin 
of the sulcus. (After Lankester and various authors.) 


B. Annulus spiral with a single pitch, sulcus slightly (Spirodinium) 
or markedly (Pouchetia) spiral, decussating the annulus at both ends. 
The transverse flagellum arises at the anterior end of the annular spire, 
the longitudinal flagellum at the posterior end of the sulcar spire. 

Spirodinium, Schutt ; Cochlodinium, Schutt ; Pouchetia, Schu'tt. All 

Pouchetia resembles Cochlodiniunt, but is distinguished by the 
possession of a complicated stigmatic apparatus consisting of a red or 
black pigmented body with one or more large refractive lens-like 
spherules adjoining it. 

The interesting genus Polykrikos, Btitschli, consists of two, four, or 
rarely eight individuals united together into a colonial organisation 
(Kofoid [10a]). It is also peculiar in the possession of nettling organs, 
and is said to present holozoic nutrition. Coasts of Europe and California. 

All Gymnodiniaceae may be naked or enclosed temporarily in a 
gelatinous membrane. The tribe includes marine and freshwater species. 


Carapace bivalve, perforated with numerous pores, without annular 
plates and without annulus, the two halves meeting directly like the 
edges of two opposed watch-glasses; longitudinal flagellum has the 
character of a tractellum with the transverse flagellum vibrating about 
its base ; chromatophores yellow ; contractile vacuoles represented by 
pusulae opening into the groove from which the flagella arise at the 
^interior end of the cell-body. 

At the time of division each daughter-cell receives one parent valve 
and forms the other anew. The Prorocentraceae are entirely marine. 

Lotsy (12) regards this tribe as being probably similar in some respects 
to the ancestors of the Diatomaceae. 

Exuviaella, Cienkowski, rounded in front and behind. Prorocentrum, 
Ehrenberg, heart-shaped, flattened, pointed behind, with rostral prolonga- 
tion of one of the valves at the anterior or flagellar end. 


These are characterised by the possession of a multitabulate cellulose 
.carapace or cuirass, each valve being composed of at least two plates 
which are frequently areolated, and, in addition, there are three or more 
mmular and sulcar plates. The longitudinal flagellum plies in the 
sulcus ; the transverse flagellum arises at the junction of sulcus and 
annulus and vibrates in the latter groove (Fig. 12). 

The cellulose membrane which constitutes the carapace or cell-wall 
of the Peridiniaceae is perforated by minute pores and is generally 
provided with processes which may take the form of horns, spines, or 
aliform expansions. 

Multiplication takes place by oblique longitudinal (rarely transverse) 
division, each daughter-cell receiving half of the parent carapace, that is 
to say, half of each valve, and regenerating the other half. Resting 
: sporocysts are enclosed in a gelatinous membrane, and it may be noted 

1 86 


that the endogenous formation of swarm-spores results in the production 
of gymnodiniform young. 

Chromatophores, indefinite in number, may be green, reddish yellow, 
or absent. The reddish-yellow variety of chlorophyll has been named 
peridiniu (Schiitt). The colour of the chromatophores turns green at 
death owing to the solubility of the peridinin. Many genera comprise 
both coloured and colourless species, but the latter are furnished with 
leucoplasts. Other plastids described as fat-forming bodies or lipoplasts- 
are also met with. 

The vacuole-system consists of saccules and pusules discharging into 
the depression from which the Hagella arise. 

The excrescences of the carapace serve as floats for these pelagic 
organisms and occur as linear (Ceratium, Fig. 11) or foliaceous 

FIG. 11. 

Ceratium tripos. Dorsal view 
shortly after fission, the two 
daughter individuals still at- 
tached to each other. , the 
anterior individual protected 
by the greater part of the 
parent's epitheca ; 6, the pos- 
terior individual protected by 
the greater part of the hypo- 
theca. (After Sohiitt.) 

FIG. 12. 

Peridiniu m divergens. Ventral view 
.showing the vacuole-system. c.p, the 
small collector-pusule surrounded by :i 
rosette of still smaller pusules which 
open into it; s.p, the large sac-pusule or 
reservoir ; both opening into the fundus 
(/), from which both the transverse flagel- 
lum (0 lying in the annulus (a) and the 
longitudinal flagellum (/) arise. (After 

(Ornithocercus, Fig. 10 (8)) expansions. At the anterior or apical end of 
the cell there is an apical pore which is frequently closed by a perforated 
plate resembling a madreporic plate (e.g. Blepharocysta}. The sulcus is 
ventral, but there is no plane of symmetry. 

Some species of Ceratium and Peridinium are found in freshwater 
lakes, but the other genera appear to be exclusively marine. 

In respect of individual numbers the principal habitat of the Peri- 
diniaceae is in the cold waters of the North Sea, Baltic, and North 
Atlantic. In point of specific divergence the southern waters are richer. 
Individual variation is often excessive, and seasonal dimorphism has also 
been noted. 

Genera and species are determined by the form of the body and by 
the characters of the cuirass. 

The Peridiniaceae are divided into four families as follows : 

FAMILY 1. GLENODINIIDAE, intermediate between Gymnodiniaceae and 
Peridiniaceae. Cuirass soft, membranous, consisting of two structureless- 


valves with an anmilus between them. Glenodinium pulvisculus, Ehrb. 
(Fig. 10 (3 and 4)). 

FAMILY 2. PTYCHODISCIDAE. Body lens -shaped, valves perforate, 
annulus soft, membranous. Ftychodiscus nocticula, Stein. 

FAMILY 3. CERATIIDAE. The typical genera are the well-known 
forms of Ceratium and Peridinium. The valves of the cuirass are described 
as the epitheca and the hypotheca respectively. The former carries the 
apical pore and the latter the sulcus. But the sulcus sometimes extends 
beyond its decussation with the annulus up the ventral side of the 
epitheca to the apex of the cell, e.g. in Steiniella, Schiitt, and Gonyaulax, 
Diesing ; or the sulcus may be short, extending equidistantly on either 
side of the annulus as in Protoceratium, Bergh. 

In the genus Ceratium we meet with two-, three-, four-, and five- 
horned varieties. The chromatophores of the freshwater species of the 
genus are green, of the marine species yellowish to brownish in colour. 

Some Ceratiidae are spherical, as Blepharocysta, Ehrb., in which the 
annulus and sulcus are only indicated by the arrangement of the plates. 
Closely allied to Blepharocysta is the genus Podolampas, St., which has a 
peridinioid form of body though a different tabulation. Others are 
fusiform like the remarkable genus Oxytoxum, Stein. In Ceratocorys 
horrida, Stein (Fig. 10 (9)), the borders of the annulus are expanded like 
the rim of a hat, while the left sulcar margin is expanded into a wing 
bearing long plumose spines. Pyrophacus is an oyster-shaped Ceratian 
in which sporulation has been observed by Schiitt. The new genera 
Hderodininin, Murrayella, Acanthodinium have recently been described by 

FAMILY 4. DIXOPHYSIDAE. The shell is divided by a sagittal suture 
into two lateral subequal portions. The epitheca is flattened and much 
smaller than the hypotlieca. The borders of the annulus are funnel- 
shaped, and minute brown-coloured corpuscles called Phaeosomata often 
occur in the space between the two superimposed funnels. The right 
sulcar border is inconspicuous, but the left border may be monstrously 
developed into wings and spines (e.g. Ornithocercus, Fig. 10 (8)). 

In Amphisolenia (Fig. 10 (7)) the epitheca is excessively reduced, consist- 
ing of two minute plates united together by a sagittal suture. The dis- 
proportionately large hypotheca in this genus consists of two elongated 
plates likewise united by a sagittal suture. The sulcus of Amphisolenia 
(Fig. 10 (7)) proceeds from the subterminal annulus along the neck of the 
cell for a distance equal to about one-quarter of the length of the body, 
terminating at a rather deep pit, representing the depression from which 
the flagella arise in other forms. This depression may be conveniently 
distinguished by the term flagellar fundus or simply the fundus. 1 

In AmphisQlcnia the protoplasmic contents of the cuirass consist of 
a nucleus, a moniliform chromatin reticulum, and several ellipsoidal 
plasmosomes of amyloid character. A pusule situated near the nucleus 
opens by a slender canal into the flagellar pore, and one or more accessory 
pusules may lie near it in the cytoplasm. 

1 The German term is "Geisselspalte." It is not a true pharyngeal pit although 
it strongly resembles one. 


Other genera of Dinophysidae are Phalacroma, St. ; Dinophysis, Ehrb. ; 
Histioneis, St. (Fig. 10 (5, 6)), Citharistes, St.; Triposolenia, Kofoid San 
Diego region of the Pacific. 


There are only three genera in this sub-class, and of these 
Nodiluca has long been known as a widely distributed organism 
that is often the principal cause of the phosphorescence of the 
surface of the sea. The other two genera are little known. 

Nodiluca possesses a sub-spherical body with bilateral symmetry, 
the median plane of symmetry being determined by an elongated 
groove on the ventral side called the peristome (Fig. 15 (5)), at the 
bottom of which is the mouth. The nutrition is holozoic, and the 
mouth leads directly into the central part of the protoplasm, from 
whence trabeculae, exhibiting in life a streaming of the granules, 
radiate outwards towards the periphery. In certain regions the 
trabeculae are concentrated in the form of dense groups of fibrillae 
giving rise to a fibrillar plexus. One such plexus arises from the 
posterior end (/) of the central protoplasm, and is inserted along a 
thickened linear area of the integument behind the peristome called 
the bacillary organ, "Staborgan" (Fig. 15 (5, c)). 

The integument consists of a resistent ectoplasm, a dense 
reticulate layer of alveolar protoplasm. The striated proboscis- 
like tentacle which arises in the middle line at the anterior end 
of the peristome, and constitutes one of the most notable features 
of its organisation, has a length equal to half the diameter of the 
sphere. It is a flattened contractile organ, convex on its outer side 
and concave on the inner adoral side. The protoplasmic trabeculae 
which traverse the tentacle are so disposed as to produce a striated 
structure comparable to that of striped muscle-fibres. 

Other peristomial organs are the dentiform process ; the flagellum, 
which is borne upon or near a protuberance termed the lip ; and 
lastly the mouth. The tooth l and the lip are placed asymmetri- 
cally upon the right wall of the peristome. The mouth occupies 
the posterior two-thirds of the fundus of the peristome, which is 
deepest behind and becomes progressively shallower in front. In 
front of the mouth, that is to say, in the anterior third of the 
peristome, are the lips, with the flagellum, the tooth, and the 
tentacle. The flagellum lies well within the peristome and requires 
practised observation for its discovery. 2 It resembles the typical 
flagellum of Mastigophora, namely, a filament of uniform thickness 
from base to apex. The tentacle can be extruded far beyond the 
confines of the peristome, but it can also be retracted, rolled up, and 
so escape superficial observation. 

' The tooth is a protoplasmic organ. - It was discovered by Krohu in 1852. 



The nucleus is lodged within the central protoplasm, and 
presents during life a transparent, homogeneous appearance. 

The ingested food is enclosed in food-vacuoles, Avhich are some- 
times so large as to occupy the greater portion of the body. No 
contractile vacuole has been observed. The products of metabolism 
consist of albuminoid and fatty granules. 

Neither the slow contractions of the tentacle nor the rapid 
vibrations of the cilium are sufficient to impart movements of pro- 
gression to the inert body of Noctiluca, which merely drifts with the 
rest of the plankton, kept afloat by its own buoyancy. The 

FIG. 13. 

Sporulation by blastogenesis in Noctiluca miliaris, Sur. A, surface view of the germinal 
disc, showing the nuclei that give rise to the nuclei of the spores. Each nucleus (n) is accom- 
panied by an archoplasmic body (a). B, cleavage-products (buds) in side view. C, L>, buds 
in process of division. The archoplasmic body () is seen to have divided before the nucleus 
(/(). K and F, later stages of blastogenesis. (After Doflein.) 

phosphorescence of Noctiluca is the manifestation of its response to- 
mechanical, electrical, thermal, and chemical stimuli. According 
to the observations of Quatrefages (quoted by Watase), " the light 
emitted from the whole body, or any of its parts, is composed of a, 
vast number of instantaneous scintillations." 

The life-history of Noctiluca comprises the phenomena of simple 
longitudinal fission (Fig. 15), resting-phase, conjugation, and blasto- 
genesis. The transition of an ordinary individual into the resting 
condition does not involve the formation of a protective cyst- 
membrane, but simply the degeneration of the peristome and its 

When two individuals come together for the purpose of con- 


jugation, they attach themselves at the peristomial region and 
gradually fuse together to form a zygote having twice the normal 
volume. The fusion of the nuclei of the conjugants has been 
observed directly, under the microscope, by Cienkowski and later 
by Plate. 

It seems likely, although still awaiting demonstration, that the 
production of swarm- spores (zoospores) by exogenous budding 
depends upon previous conjugation. 

The production of buds is limited to a particular area of the 
sphere, namely, the area corresponding with the peristomial region 

where the central protoplasm is massed. 
The cleavage of nucleus and protoplasm 
proceeds in a manner analogous to the 
discoidal cleavage of a yolk-laden egg 
(Biitschli). .Nearly all the parent pro- 
toplasm is used up in the formation of 
FIG. 14. the buds, the full number of which 

Two ripe spores of Noctttum amounts to 512. 
mlliarls, showing n. nucleus; /', m, i ' < i i 

flageiium ; 6, the body interpreted Ihe phenomena of karyokmesis in 

to,be a blepharoblast or a centro- Nnriiliirn Tvrpsjpnl- cnmp inrprpstino- 
some. (After Ishikawa.) present Testing 

features. There is outside the nuclear 

membrane, but in the neighbourhood of the nucleus, a relatively 
large archoplasmic body. Before division of the nucleus occurs, 
this body elongates to assume a dumb-bell shape (Fig. 3, A), Avith 
an aster at each end. The chromatin of the nucleus concentrates 
into a number of elongated moniliform chromosomes, and then the 
nucleus warps itself round the central part of the archoplasmic 
body, forming a spindle-like body round the achromatic spindle of 
the archoplasmic body (Fig. 3, B). Finally, the chromosomes 
divide into two parties, which travel to the opposite poles of the 
spindle, and then both nucleus and archoplasm divide transversely. 

The buds project from the surface of the body, but remain 
attached to it until all have attained a certain size, and until each 
has acquired its flagellum, which represents the cilium of the adult 

The detached free-swimming buds have a dinoflagellate appear- 
ance, and it may be broadly stated that the blastogenesis of 
Nodiluca, results in the formation of gymnodiniform young (Fig. 
14). The growth of the young into the adult condition has not 
been observed. 

The sub-class contains only three genera: Nodiluca, Suriray, 0'3-1'25 
mm., probably cosmopolitan; Leptodiscus, Hertwig, G'6-1'5 mm. ; and 
Craspedotella, Kofoid (8), 0'15-0'18 mm. E. Pacific. Craspedotella has 
a strong resemblance to a craspedote medusa in form, being bell-shaped 
and having a distinct velum at the margin. 



Fio. 15. 

Nwtiluca miliaris, Suriray. 1, 2, two stages in the longitudinal lission ; n, nucleus ; N, 
food - particles ; t, tentacle. 3, aboral view; a, entrance to the peristome ; c, the bacillary 
organ ; d, the tentacle ; ft, the nucleus. 4, the animal acted upon by iodine solution, showing 
the protoplasm like the "primordial utricle" of a vegetable cell shrunk away from the cuirass. 
5, lateral view, showing (a) the entrance to the peristome in which 6 is placed ; <;, the bacillary 
organ ; <?, the tentacle ; e, the mouth and pharynx, in which the flagellum is situated ; /, broad 
plexus of tibrillae passing from the central protoplasm to the bacillary organs; h, nucleus. 
After Lankester.) 


This division of the Mastigophora affords an apparent transition 
from the Flagellata to the Radiolaria. It is monotypic, compris- 
ing the single species Distephanus speculum, Stohr, which is para- 
sitic upon or commensal with Radiolaria, and while possessing a 
flagellum, has also a fenestrated siliceous skeleton. 


Since the publication of Biitschli's treatise on the Mastigophora in Bronn's 
Klassen und Ordnungen dcs Tfiicrreichs, Bd. i. Abth. 2, 1885, this class of 
Protozoa has received the fullest general treatment in the pages of Engler and 


Fraud's Die naturlichen Pflanzenfamilien, where the Flagellata have been 
written upon by G. Senn (Leipzig, 1900) ; the Peridiniales by F. Schiitt (1896) ; 
and the Volvocaceae by N. Wille. Further references will be found in the 
bibliography appended to the volume on the Protozoa by G. N. Calkins in the 
Columbia University Biological Series (1901). 

In the following list will be found references to some of the principal papers 
mentioned in the text : 

1. Apstein, C. Pyrocystis lunula. Lab. inter. Meeresforsch. Kiel, viii., 1906, 

p. 263. 

2. Biackman, F. F., and Tansley, A. G. A Revision of the Classification of 

the Green Algae. New Phytol. i., 1902. 

3. Dobell, C. C. Structure and Life-History of Copromonas. Q. J. Micr. Sci. 

lii., 1908, p. 75. 

4. Goldschmidt, R. Lebensgeschichte der Mastigambben. Arch. Prot. Suppl., 

1907, p. 83. 

5. Hartman, M., and von Prowazek, S. Blepharoblast, Caryosom und 

Centrosom. Arch. Prot. x., 1907, p. 307. 

6. Hickson, S. J. Reproduction and Life-History of the Protozoa. Trans, 

Manch. Micr. Soc., 1900. 

7. Keeble, F. W., and Gamble, F. W. The -Green Cells of Convoluta. Q. J. 

Micr. Sci. li., 1907, p. 167. 

8. Kofoid, C. A. Craspedotella. Bull. Mus. Harvard, xlvi. 9, 1905. 

9. New Species of Dinoflagellates. Ibid. 1. 6, 1907. 

10. Dinoflagellata of San Diego. Univ. California Pub. Zool. ii. 8, 

1906 ; Hi. 6, 7, and 8, 1906 ; and Hi. 13, 1907. 

10a. Polykrikos. Zool. Anz. xxxi., 1907, p. 291. 

11. Lohmann, If. Die Coccolithophoridae. Arch. Prot. i., 1902, p. 89. 

12. Lotsy, J. P. Vortrage liber botanische Stammesgeschichte. Jena, 1907. 

13. Minchin, A. E. Investigations on the Development of Trypanosomes. 

Q. J. Micr. Sci. Hi., 1908. 

14. Moore, J. E. S. The Cytology of the Trypanosomes. Ann. Trop. Med. i., 


15. Murray, G., and Blackman, V. H. The Nature of the Coccospheres and 

Rhabdospheres. Phil. Trans, vol. cxc., 1898, p. 427. 

16. Prowazek, S. von. Flagellatenstudien. Arch. Prot. ii., 1903, p. 195. 

17. Untersuchungen iiber einige parasitische Flagellaten. Arb. k. 

Gesundheitsamte, xxi., 1904, p. 1. 

18. Robertson, M. Pseudospora volvocis. Q. J. Micr. Sci. xlix., 1905, p. 213. 

19. Schaudinn, F. Generations- und Wirtswechsel bei Trypanosoma. Arb. k. 

Gesundheitsamte, xix., 1902, p. 169. 

20. Untersuchungeu iiber die Fortpflanzung einiger Rhizopoden. Ibid. 

1903, p. 547. 

21. Wenyon, C. M. Observations on the Protozoa in the Intestines of Mice. 

Arch. Prot. Suppl., 1907, p. 169. 

22. West, G. S. A Treatise on the British Freshwater Algae. Cambridge, 


23. Woronin. Chromophyton rosanqffii. Bot. Ztg., 1880. 

24. Zederbauer, E. Geschlechtliche u. ungeschlechtliche Fortpflanzung von 

Ceratiwn. Ber. d. D. bot. Gesell. xxii. 1, 1904. 

THE PROTOZOA (continued) 


Order Lissoflagellata. 2 
Sub-Order MONADINA. 

Genus Trypanomorpha. 


Genera Trypanophis, Trypanoplasma, 
and Trypanosoma. 


THE Haemoflagellates, or Trypanosomes, although possessing in 
common a uniform type of organisation, probably do not all belong 
to a single, well-defined group of monophyletic origin. They are 
preferably regarded as an assemblage of forms which have sprung 
from two quite different stocks, the resemblances exhibited being 
due to convergence, brought about by the acquirement of similar 
adaptations in response to their similar and highly specialised mode 
of life. They are entirely parasitic, their characteristic habitat 
being the blood of a Vertebrate ; and, as is well known, certain of 
them are the cause of severe, often fatal illness. 

The Haemoflagellates possess either one or two flagella. When 
there are two, they originate close together, at or near the anterior 
end of the body. One is free and directed forwards ; the other 
turns back and is attached for the greater part of its length to the 
side of the body, by means of an undulating membrane, ultimately 
terminating in a free portion directed posteriorly. Thus a Hetero- 
mastigine condition is found. When only one flagellum is present 

1 By H. M. Woodcock, D.Sc. (Loud.), Assistant to the University Professor of 

2 The classification of the Flagellates here made use of differs somewhat from that 
adopted in the account of the Mastigophora. The position of the Trypanosomes 
according to that scheme will be seen on reference to pp. 167, 168. 

193 13 



it is invariably attached in this manner, but the flagellum is 
probably not homologous in all these cases. In certain Trypano- 
somes which are to be derived from a Monadine ancestor, it is, of 
course, the single flagellum that is represented, with the free part 
directed anteriorly ; other forms, however, are rather to be looked 
upon as derived from a Heteromastigine ancestor, the flagellum 
that persists being the trailing, posteriorly directed one (the 
so-called " Schleppgeissel"). 1 There are two nuclear bodies, one, 
the trophonucleus, regulating the trophic life of the cell, the other, 
the kinetonucleus, directing its locomotor activities. 

FIG. 1. 
" Undulina ranarum," Lankester, 1871. In 13 the nucleus is shown. 

The most general method of reproduction is by binary, longi- 
tudinal fission ; but multiple division or segmentation is also met 
with. As regards the life-cycle of the parasites, only little is as 
yet known in most cases. From the results of the most recent 
researches, however, it certainly appears probable that, apart from 
various blood - sucking Invertebrates which may (mechanically) 
transmit a given parasite, there is, in general, a true alternate host 
for each form ; one, that is, in which definite phases of the life- 
cycle including, most likely, sexual conjugation are normally 
undergone. Further knowledge on this subject is greatly needed. 

Historical. The first observation of a Trypanosome is probably 
to be ascribed to Valentin, who, in 1841, announced his discovery 

1 This flagellum is also termed the gubernaculum (see p. 159). 



of Amoeba-\ike parasites in the blood of a trout. In the two or 
three years following, Remak, Berg, and others recorded the 
occurrence of Htiematozoa which were undoubtedly Trypanosomes 
in different fishes. The parasite of frogs was first seen by Gluge 
(1842), and in July 1843 Mayer described and figured certain 
corkscrew-like and amoeboid organisms from the blood of the same 
animal, which he termed variously Amoeba rotatoria and Paramoecium 
costatmn or loricatum. A few months later (November) Gruby also 
published (24) an account of this parasite, to which he gave the new 
generic name of Trypanosoma. The same form was subsequently 
described and figured by Lankester (30) in 1871, who, unaware of 
Gruby 's work, called it Undulina ranarum ; this author was the 
first to indicate the presence of a nucleus in the organism (Fig. 1, B). 
The well-known parasite of rats was discovered by Lewis, in India, in 
1878, and was afterwards named Herpetomonas lewisi by Kent. 1 It 
is to Mitrophanow (1883 to 1884) and Danilewsky (1885 to 1889), 
however, that we owe the first serious attempts to study the com- 
parative anatomy of these 
Haematozoa. The work of 
the latter researcher in par- 
ticular is deserving of recog- 
nition, especially when the 
primitive state of knowledge 
in regard to blood-technique 
in those days is borne in 
mind. Some of Danilewsky's 
figures of a Trypanosome of 
birds are reproduced in Fig. 2. 
Trypanosomes were first 
met with in cases of disease 
by Griffith Evans, who, in 
1880, found them in the blood 
of horses suffering from Surra 
in India. The organisms were 
thought by him to be Spirilla. 
Steel rediscovered the same 
form a few years later and 
took a similar view of its 
affinities, naming it Spirochaeta 
evansi. In 1894 Bruce found the celebrated South African parasite 
( T. bnicii) in the blood of cattle and horses laid low with Nagana, 
or Tsetse-fly disease ; and this worker subsequently demonstrated, 
in a brilliant manner, the essential part played by the fly in trans- 
mitting the parasite. Brace's discovery may be said to have 
inaugurated a rapid increase in the number of known forms, the 

1 This form is now placed in the genus Trypanosoma. 

A-C, different forms of Trypanosoma, sangulnis 
avium, Danilewsky. D, the same parasite dividing 
longitudinally . n, nucleus ; u.m, undulating mem- 
brane ; /, nagellum. (After Danilewsky.) 


knowledge of which has in many cases thrown light upon the 
etiology of maladies previously obscure. Thus, two characteristic 
diseases, Dourine, which afflicts horses and mules in Northern 
Africa and the Mediterranean littoral, and Mai de Caderas of 
horses in South America, were next shown to be caused by 
different Trypanosomes ; and since then many other varieties of 
trypanosomosis have been described, chiefly from Africa, the home 
of the dreaded Tsetse-fly. 

Prominent among them, unfortunately, is human trypanosomosis. 
The credit for first recognising a Trypanosome in human blood, 
and describing it as such, must undoubtedly be assigned to Nepveu 
(1898). The parasites were not definitely associated with disease, 
however, till 1901, when they were seen in the blood of a European 
in Senegambia suffering from intermittent fever. Forde first found 
the organisms, but was uncertain of their nature ; he showed them 
to Button, who recognised them as Trypanosomes, and gave this 
form the name of Trypanosoma gambiense. A year later (1902) 
Castellani discovered what has been shown to be the same parasite in 
the cerebro-spinal fluid of patients suffering from sleeping-sickness 
in Uganda, and it has since been conclusively proved by Bruce 
and Nabarro that this organism is the true cause of that terrible 

More important, however, from the standpoint of Protozoology, 
than these interesting medical discoveries have been the investigations 
by Brumpt, Laveran and Mesnil, Le"ger, Minchin, Schaudinn, the 
Sergents, and others during the last few years upon numerous other, 
mostly " tolerated " forms ; to their researches, indeed, we owe most 
of our knowledge at the present time, relating to the life-cycle of 
the Haemoflagellates. And it is fitting, here, to pay a tribute to 
the value of the characteristic stain first made known by Roman- 
owsky, and its subsequent modifications (e.g. those of Giemsa, 
Laveran, Leishman, etc.), without which, it is safe to say, thi 
progress would have been impossible. 



(a) Occurrence and Transmission. 

Trypanosomes are harboured by members of all the chief classes 
of Vertebrates, with the exception of Cyclostomes. Mammals, birds, 
and fishes furnish, however, by far the greater number of hosts. Fewer 
parasites have been described from Amphibia, and up till now only 
from frogs ; while, among Reptiles, their occurrence has only been 
observed in two or three instances. Data with regard to the 
frequency with which individual species are to be met with, in any 


particular kind of host, are as yet somewhat scanty. In one or 
two cases, however, the parasites are known to be fairly common. 
Trypanosoina lewisi, for example, occurs in a considerable percentage 
of sewer -rats throughout the world, having accompanied these 
rodents in their ubiquitous migrations ; the proportion of hosts 
infected varies usually from 10 to 40 per cent. 

In considering the occurrence of Trypanosomes in Mammals 
careful distinction must be drawn between true or natural hosts 
and strange or casual ones. In the former case, by reason of the 
long-existing association between host and parasite, a condition of 
mutual toleration has been reached, which, in ordinary circum- 
stances, enables a proper balance to be maintained on both sides. 
On the other hand, when a Trypanosome gains an entry into 
animals Avhich have never been previously liable, by their dis- 
tribution, to its invasion, and which are consequently unaccustomed 
and unadapted to the organism, it usually produces markedly 
harmful effects. Such a state of affairs has resulted, for example, 
from the march of civilisation into the " hinterlands " of the 
various Colonies, where man, together with the numerous domestic 
animals which accompany him, has been brought into proximity to 
big game, etc., and what is equally important, into the zone of the 
blood-sucking insects which prey upon the same. 

Very many of the common domestic Mammals can be success- 
fully infected (either in an accidental way or else artificially) with 
different " pathogenic " Trypanosomes, to which they succumb 
more or less readily ; they cannot be regarded, however, as natural 
hosts of those Trypanosomes. In considering disease-causing forms, 
the more narrowly the original source of the parasite concerned is 
defined, the closer do we get to the true Vertebrate host or hosts. 
In the case of the Nagana parasite, it has been shown that such are 
almost certainly to be found among buffaloes and various Antilo- 
pidae (e.g. the gnu, "koodoo," etc.), while, again, the native host of 
T. equinum, of Mai de Caderas in South America, is most probably 
the capybara. It may be said undoubtedly, with regard to the 
many lethal Trypanosomes now known, that there is, in each case, 
some indigenous wild animal tolerant of that particular form, 
which serves as a latent source of supply to strange Mammals 
coming into the vicinity. 

Transmission. In the transmission of the parasites from one 
Vertebrate individual to another, a blood-sucking Invertebrate is 
almost invariably concerned. 1 In the case of all Trypanosomes of 

1 Trypanosoina equiperdum, the cause of Dourine or horse-syphilis, is conveyed by 
the act of coitus ; and it is quite uncertain whether this parasite is ever transmitted 
naturally by an insect. Moreover, Koch has recently brought forward evidence 
(29, Schluss - Bericht) which, he thinks, tends to show that the human parasite 
(T. gambiense) can also lie transmitted by sexual intercourse. 


warm-blooded Vertebrates for which the transmitting agent is 
known, this is an insect, generally a member of the Diptera ; in 
that of Trypanosomes of cold-blooded Vertebrates the same role is 
usually played by an Ichthyobdellid leech (Piscine forms), but 
possibly now and again by an Ixodes (some Amphibian or Eeptilian 

The actual relation between the parasite and the transmitting 
Invertebrate has long been questioned, and there are still some 
very important instances in which the real state of affairs is not 
certain. But it would seem, from the. results of recent work, 
that in most cases some Invertebrate or other acts as a true 
alternate host. Thus, so far as leeches are concerned in connec- 
tion with the Trypanosomes of fishes, the investigations of Leger 
(50), Brumpt (10-12), and Keysselitz (27) have made it clear that 
the parasites not only live quite normally, but undergo a definite 
evolution in particular organs of leeches which have fed on infected 
fish. Frequently this further development can only proceed, at 
least to its full extent, in a certain leech to the exclusion of others 
(e.g. in a Hemiclepsis and not in a Piscicola, or vice versa) ; this restric- 
tion points distinctly to the leech in question being a specific natural 
host. Again, according to the celebrated researches of Schaudinn 
(75) on an Avian Trypanosome, Trypanomarpka (Trypanosoma) 
noctuae, a species of gnat (Culex) provides the alternate host, 
in which a complex part of the life -cycle takes place. It is 
interesting to note that, as might be expected, there is a regular 
periodicity in the infectivity of the gnat ; that is, it can only 
transmit the infection after such and such an interval has elapsed 
since the meal when it became itself infected. Coming, lastly, to 
the Mammalian forms, Prowazek (68) has described phases of 
development of T. lewisi in the rat-louse (Haematopinus sp.), 
and considers that this insect serves as a true Invertebrate host ; 
though he was not able to prove the actual transmission of the 
parasites back to the rat by means of it. 1 

Interest and discussion has mostly centred, however, upon the 
part played by the transmitters of the lethal Trypanosomes, and 
it is only quite recently that any light can be said to have been 
thrown upon the subject. 

It has for some time been generally recognised that, in many cases at 
any rate, a particular biting-fly is chiefly responsible for the spread of a 
particular parasite in an infective district. In such cases, a striking 
coincidence usually exists between the area over which a certain trypanoso- 
mosis is prevalent and the zone of distribution of a certain fly. Thus, of 
two well-known African Trypanosomes, one, T. briicii, the cause of Nagana 

1 This has been effected, however, by earlier observers (Rabinowitsch and 
Kempner) by means of fleas, which are possibly the " right " insects. 



or Tsetse-fly disease in South-East Africa, is conveyed by Glossina morsitans l 
(Fig. 3, A and B), while the other, T. gambieiise, the cause of sleeping- 
sickness, has for its carrier in Uganda another Tsetse-fly, G. palpalis. 

Working upon this knowledge, many investigators have at one time 
or another performed series of experiments with a view to finding out 
whether any developmental cycle is undergone by the parasites while in 
the fly, and whether definite periods of infectivity occur, on the analogy 
of the malarial parasites in mosquitoes. The earlier results obtained 
seemed to indicate that the role of the fly was purely mechanical the 
insect acting merely like an artificial inoculating tube. Bruce, in the 
course of his pioneer work in Zululand, found that the flies could, with 


Various blood-sui-king flics. A and B, Glossina morsitans (transmits Trypanosmna brurii, 
of Nagana), x 2 ; C, Hipi>(H>oscu rufipes (thought to transmit T. thdleri, the cause of " bile-sick- 
iii-ss"), x U; I), Tn.lH.inns Uneola (probably conveys the Surra parasite, T. evansi), x 1J ; E, 
Mnitin.Ti/.- -i-ii], -itfi'na (suspected in connection with T. equinvm, of Mai de Caderas), x 2J. (A and 
B from Lav. and Mesn., after Bruce ; C after L. and M. ; D and B after Salmon and Stiles.) 

varying success, infect a healthy animal if allowed to bite it up to forty- 
eight hours after being themselves fed on an infected one, but not after- 
wards. Similarly, Bruce, Nabarro, and Greig (8) ascertained that G. 
palpalis could give rise to an infection eiht, twenty-four, or forty-eight 
hours after feeding, but after two days they could no longer obtain a 
successful inoculation. Moreover, some experiments extended over two 
months gave no sign of any periodicity of infection. Nevertheless, these 
workers found that the Trypanosomes could at all events live and retain 
their mobility in the stomach of the fly up to seventy-one hours. 

Similar results were obtained by Minchin, Gray, and Tulloch. In 
their interesting report (59) these authors state that they could find 
no evidence of a fly becoming infectious at any particular period after 

1 Tliis parasite is also conveyed, in different districts, by G. pallidipe!! and 


being fed, experiments being carried out up to an interval of twenty-two 
days. An additional and significant fact remarked upon by them is that 
only the first animal which the experimental fly was allowed to stab 
became infected ; if the insect was removed before its meal was completed 
and immediately placed on another animal, this latter did not become 
infected. That is to say, after a fly had been allowed to, as it were, clean 
its proboscis from the Trypanosomes remaining in it since its previous 
meal (on an infected animal), it was no longer infectious. 

These facts make it certain that Trypanosomes can be and are 
conveyed by Tsetse-flies in a purely direct and mechanical manner ; 
and so far as T. gambiense and sleeping-sickness in Uganda are 
concerned, it is probable that their spread, through the agency of 
G. palpalis, has been largely if not entirely in this way. But this 
does not by any means end the matter. 

Minchin, Gray, and Tulloch bring forward observations which 
point to a commencing cycle of development of T. gambiense 1 in the 
fly. Up to forty-eight hours the Trypanosomes present in the 
stomach of an infected fly are markedly differentiated into two 
types, which probably represent sexual forms. After forty-eight 
hours a type of more indifferent character makes its appearance, 
which usually becomes scanty with lapse of time, till at ninety-six 
hours scarcely a Trypanosome can be found. It is interesting to 
note that during this interval the parasites steadily increase in 
size. Coming next to Koch's recent investigations on behalf of 
the German Sleeping- Sickness Commission, a very important 
observation is recorded (29). A species of Glossina, distinct from 
G. palpalis, namely, G. fusca, was bred in captivity ; the individuals 
born and reared under these conditions were regarded as certainly 
free from Trypanosomes. 2 Several of these flies were fed on rats 
infected with T. gambiense. They were examined from ten to 
twelve days later, and after this long interval were found to be 
infected with those parasites. Moreover, individuals of another 
Tsetse-fly, G. tachinoides, similarly fed, were also found to contain 
T. gambiense after the same lengthy interval. 

Still more recently Stuhlmann (80), in his description of G. 
fusca, has published some extremely interesting notes on the relation 
of T. bnicii to this fly. Using reared flies, considered to be certainly 
free from infection, Stuhlmann was able to infect about 80 to 90 

1 The case of T. gambiense in Glossina palpalis is unfortunately complicated by 
the occurrence in the same species of fly of other Trypanosomes, distinguished by 
Novy(61) as " fly-Trypanosomes. " One of these, T. grayi, at any rate is entirely 
ditferent from T. ganibiense ; and it is highly probable that some of the observers (e.g. 
Gray and Tulloch [23], Koch [28]), who first described what they regarded as 
developmental phases of T. gambiense, were dealing in reality with T. grayi. 

2 This is on the assumption, of course, that the parasites were not inherited ; but 
most authorities seem to be agreed that hereditary transmission of Trypanosomes by 
Tsetse-flies does not take place. 


per cent, and in from two to four days was able to observe various 
developmental phases of the parasites. This further development 
continued on the flies being fed upon healthy animals, but only in 
about 10 per cent of the individuals ; in the rest it gradually dis- 
appeared. This percentage, it is instructive to observe, was about 
the same as that of the Tsetses (G. fusca) found to be infected with 
T. brucii (in all probability) in nature. 

It will be seen that it is impossible to draw any certain con- 
clusions from the present position of the problem. Nevertheless, 
there is good reason to suppose that, for a given lethal Trypano- 
some, there is a particular insect which is a true alternate host. 1 
It seems very probable that here, as among leeches, there are 
right and wrong hosts for the parasites ; that while the com- 
plete normal development, culminating in the transfer back to the 
Vertebrate, can only take place in a certain species of fly, attempts 
at development which are, to a varying degree, partially successful 
may go on in other biting- flies ; these latter, however, being 
able to act in relation to the Vertebrate host only as mechanical 

Before leaving this question of the mode of transmission of 
Trypanosomes, it is to be noted that Minchin has put forward (57) 
an entirely new view with regard to the method of infection. His 
idea is based especially upon the highly interesting discovery made 
by him of the occurrence of cysts, doubtless for external dissemina- 
tion by way of the anus, in one of the " fly - Trypanosomes," 
Trypanosoma grayi. Minchin suggests that there may be two 
varieties of cyclical infection among the Haemoflagellates ; in the 
.one, the parasite undergoes cyst-formation in the insect, resulting 
in a contaminative infection of the Vertebrate, by means of its food 
or drink ; in the other, distinguished as the inoculative type, the 
infection takes place through the proboscis of the fly (as, for 
example, in the malarial parasites). Up to the present, however, 
T. grayi remains the only known form in the case of which infection 
is most probably of the first type. 2 From what has been learnt so 
far of the development of other Trypanosomes Avhether in leeches 
or in insects the distribution of the parasites in the body (see 
under " Habitat") points at any rate to inoculative infection of the 
Vertebrate. The possibility of the occurrence of both modes in any 
.one Trypanosome is not, so far as is known, excluded ; but there 
is, as yet, no definite evidence in favour of this. 

1 For further remarks bearing on this point, see pp. 230-231, 261. 

2 Although the Vertebrate host of T. grnyi has not been actually demonstrated, 
both Minchin and others have made an important observation in connection with the 
biology of the Tsetse-tty, which taken in conjunction with the non-occurrence of 
hereditary infection seems to show that it is impossible for the parasites to be 
merely fly-Trypanosomes. This is to the effect that the Tsetses, unlike mosquitoes, 
/eed only on blood, never on foul or decaying matter of any kind. 


(b) Habitat and Effects on Ho.<f. 

1. Relation to the Invertebrate Host. Schaudinn, in his work on 
the parasites of an owl (Athene noctua) (I.e.), has described in full 
the distribution and course of development of Trypanosomes in the 
body of a gnat (Culex pipiens). Although, as is pointed out below 
(see under "Life-Cycle"), it is now disputed how far Schaudinn's 
description actually relates to Avian Trypanosomes, the great 
interest excited by this author's work renders a brief abstract of 
his account necessary. 


Fie. 4. 

Diagrammatical longitudinal section through Culex pipiens to show the distribution of thff 
parasites. The arrows indicate the direction of their movement, the cTusters of stars the place* 
of agglomeration, u.l, upper lip ; LI, lower lip; tip, hypopharynx ; ph, pharynx; s.g, salivary 
gland ; ocs, oesophagus ; o.d, oesophageal diverticula (gas reservoirs) ; prov, proventriculus ; 
st, stomach ; m.t, Malpighian tubes ; c, junction of ileum and colon ; aort, aorta. (After 

The distribution of the parasites 1 is intimately connected with the 
process of digestion. Towards the end of the digestion of the imbibed 
blood, the Trypanosomes, after a period of multiplication, enter upon ;v 
resting phase, and are found either attached to or between the epithelial 
cells. After a second meal another multiplicative period occurs, and the 
parasites gradually collect in the anterior part of the stomach, where the 
nutriment remains longest unabsorbed. Here (Fig. 4, prov) the organisms 
begin to cluster in large numbers, being able to penetrate the delicate 
surface of the layer of invaginated oesophageal epithelium in this region. 
Finally, there is an enormous accumulation of the Trypanosomes at this 
place, all arranged in rows and in a resting condition. The next inflow 

1 Tliis summary relates to the first of the two parasites described by Schauiliim, 
Trypanomorptia (Trypanosoma} noctnae. 


of blood drives this mass before it, in the form of a rolled-up ball, until 
it reaches the junction of the ileum and colon (Fig. 4, c), the narrowest 
point of the intestine. The wall here is very thin and easily ruptured, 
and most of the Trypanosomes pass through it, into the vascular lacunae 
around, whence they are carried to the heart. Finally, the parasites 
become arrested in the sinus surrounding the pumping-organ of the 
pharynx, where they continue to multiply and collect again into 
agglomerated masses, which press on the wall of the pharynx in this 
region. By the end of the third digestive period, these clumps of 
Trypanosomes have broken through, and partly block up the lumen ; 
and in the next biting act they are forcibly ejected into the blood of the 
owl. Thus the parasites cannot leave the gnat until the fourth meal, 
including that which effected their entry, has taken place ; and Schaudinn 
found that the shortest time elapsing between entrance and exit was seven 
or eight days, when the insects were maintained at the optimum tempera- 
ture for digestion. 

An interesting discovery is the occurrence of true hereditary infection. 
After breaking through the wall of the colon, a few of the Trypanosomes, 
usually females, instead of being carried forwards, may pass to the 
ovarian follicles, penetrate into the young eggs, and so infect a succeeding 

According to Prowazek (I.e.), the behaviour of Trypanosoma 
hwisi in Haematopmus and its passage through the louse resembles 
in the main the account above summarised. Such differences as 
there are stand in close relation, on the one hand, to the somewhat 
different mode of feeding and of absorption of nutriment in the 
louse, and on the other hand to the fact that T. hwisi appears to 
be more resistant to " external " influences. 

With regard to other Mammalian Trypanosomes, the evidence 
so far available is mostly to the effect that they are confined entirely 
to the alimentary canal, and never occur in other organs of the 
insect. Concerning T. gambiense in G. palpalis, Minchin, Gray, 
and Tulloch (I.e.) remark that these parasites were found only in 
the mid-gut, and never passed either backwards into the proctodaeum 
or forwards into the proventriculus. 1 According to Stuhlmann (I.e.), 
T. brucii is apparently much more at home in G. fusca (which may 
prove to be its true specific host), being met with in different forms 
from the hind-gut (colon) to the proboscis. But this author also 
emphasises the fact that the Trypanosomes were never observed 
anywhere else, and, particularly, never in the salivary glands. The 
only positive observation of the occurrence of Trypanosomes in the 
salivary glands which need be taken into account is the recent 
statement made by Koch (29) that, of the different types which 

1 Gray and Tulloch (/.c.) stated that they had observed T. gambiense in the 
salivary glands, but Minchin has since shown that what they took to be salivary 
glands was in reality proventriculns ; moreover, they may have been dealing, not with 
T. gambiense, but with one of the other parasites in this fly. 


he noticed in Glossinae (sp. not given), one which from its entire 
agreement with T. gambiense was to be identified with that form 
occurred in two instances in the salivary glands. If this observation 
be corroborated, its importance is, of course, very great. 

Several important facts have been lately brought forward by 
Brumpt (10-12), which tend to show that the habitat of Piscine 
Trypanosomes in leeches is also restricted to the alimentary canal. 1 
Three types of behaviour can be distinguished, (a) The parasites 
develop solely in the stomach and never pass into the intestine or 
into the sheath of the proboscis. At the moment when the leech 
sucks the blood of another fish, the Trypanosomes pass into the 
latter directly, by way of the proboscis. This mode is exemplified 
by T. remaki of the pike. (/>) The development begins in the 
stomach and is continued in the intestine, where the parasites may 
remain for a long while. From the intestine the Trypanosomes 
pass back into the stomach, to gain at length the proboscis-sheath. 
T. granulosum of the eel is an example of this type. In the third 
variety (c) the development goes on in the stomach, but the para- 
sites succeed in passing finally into the proboscis -sheath; ex.: 
T. danilewskyi of the carp. In the case of certain marine forms 
(T. raiae and T. scyllii), whose development goes on in Pontobdella, 
Brumpt found the parasites in the stomach and intestine, but could 
not ascertain how they got back into the fish. Miss Robertson, 
however, has lately described (72) various developmental phases 
of a Trypanosome which she regards as identical with T. raiae, and 
states that small slender forms do migrate up into the proboscis : 
it is probably these which serve to infect the Vertebrate. 

2. Relation to tlie Vertebrate Host. Once an entrance into the 
blood is effected, the parasites pass rapidly into the general circula- 
tion, and are thus carried to all parts of the body. In considering the 
distribution and numerical abundance or otherwise of the Trypano- 
somes in any given individual, it is necessary to bear in mind 
whether they are in a tolerant host or in an unaccustomed one. 
Dealing with the former case first, the trend of observation points 
to their being usually rather scarce, sometimes very rare. The 
reason for this scarcity is probably the fact that multiplicative 
phases are very rarely met with, at all events in the general 
circulation. Except for a short period at the beginning of the 
infection, multiplication appears to be largely in abeyance ; this has 
been well shown by Laveran and Mesnil (37) in the case of T. 
lewisi of the rat. The parasites are often more numerous in the 
spleen, bone-marrow, kidneys, and liver than elsewhere ; and it has 
been found that multiplication goes on rather more actively in the 
capillaries of these organs. One very important point may be 

1 Brumpt has recently noted (14), however, cases of hereditary infection of leeches, 
with both Trypanosoma and Trypanoplasma. 



conveniently mentioned here, namely, that hereditary infection of the 
Vertebrate host is not known to occur in the case of most of 
the great classes. Moreover, in Mammals, whether tolerant or 
unaccustomed hosts, the parasites appear to be, as a general rule, 
unable to traverse the (uninjured) placenta. Pricolo has recently 
stated, however (67), that he has found T. duttoni in the foetus 
of an infected mouse, and thinks this a case of true hereditary 

The Trypanosomes in the active, motile form are always free in 
the blood-plasma (intercorpuscular). It is very uncertain whether 
the parasites ever come into relation with the blood -corpuscles. 
According to Schaudinn's investigation on two Avian forms, one, 
namely, Trypanomorpha(Trypanosoina}noduae, becomes in certain phases 
attached to a red blood-corpuscle (ectocorpuscular), while at other 
times it penetrates inside the corpuscle (endocorpuscular) and eventu- 
ally destroys it. The other form, Trypanosoma (Spirochaeta} ziemanni, 
apparently draws up into itself the white corpuscle (leucocyte) to- 
which it becomes attached. It must be admitted, however, that 
some doubt exists as to these alleged occurrences. 1 In addition 
there are two or three very positive statements of observations 
showing that other Trypanosomes, including Mammalian forms, 
may come into relation with the red corpuscles ; see BufFard and 
Schneider (16) with regard to T. equiperdum, and Voges (85) with 
regard to T. equinum. On the other hand, Prowazek (68) could 
find neither an ecto- nor an endocorpuscular condition in T. lemsi, 
and considers that the habitat of this parasite is restricted to 
the plasma. 

Considering now the Trypano- 
somes in an unaccustomed Mam- 
malian host, for which they are 
lethal, the parasites may either 
remain infrequent or rare some- 
times, indeed, being unnoticed until 
shortly before death or they may 
soon become numerous and go on 
increasing (Fig. 5). In the latter 
case the disease is acute and rapidly 
fatal ; in the former it is more chronic 

and lasts much longer, often several gjg^ ! Wit* ; b, 

There is often considerable varia- 
bility with regard to the appearance and number of the parasites in 

1 It is said that Schaudinu has mistaken two distinct Haemosporidian parasites, 
a Hcdteridium and a Leucocytozoon, for resting-phases of these otber Haematozoa (see 
under " Life-Cycle "). 

FIG. 5. 

Trypanosoma i'/n/y>r/v/ii;/) (of Dourine), 
eight days after 
ites ; b, blood- 
corpuscles. (After Doflein.) 


the blood at any moment. Occasionally and at irregular intervals, 
evidently following upon a period of multiplication, the Trypano- 
somes may be fairly numerous, their appearance frequently coinciding 
with an access of fever. At other times, they seem to vanish almost 
entirely from the peripheral circulation ; for what reason, however, 
is not certain. Some authorities attribute it to the rise in tempera- 
ture, as being unfavourable to the parasites ; others think it is 
due to the more potent operation of chemical and physiological 
defensive agencies of the host at a higher temperature. However 
this may be, it has long been known that certain of the organisms 
situated, probably, in some internal, more favourable part of the 
body can survive and give rise later to a fresh succession of 
parasites in the blood. 1 

The main features of the illness show a general agreement, 
whichever variety of trypanosomosis is considered; one symptom 
may be, of course, more marked than another in a particular type. 
The pathogenic effects are chiefly referable to disorganisation either 
of the circulatory or of the nervous system, or of both combined. 

Fever always occurs, at some time or other, during the course of the 
malady. Its manifestation is extremely irregular, both in character and 
in time of occurrence, and it is, therefore, usually readily distinguishable 
from malarial fever. There is, particularly in chronic cases, marked and 
progressive anaemia and emaciation, leading to pronounced enfeeblement, 
which is, in fact, the most characteristic symptom of naturally occurring 
trypanosomosis. A common feature is the occurrence of oedematous 
swellings in various parts, chiefly in the neighbourhood of the genitals, 
of the abdomen, and around the eyes. The parasites are often more 
numerous in the bloody serosities bordering these places than in the 
general circulation. This fact is of great importance in connection with 
the transmission of Dourine. In this disease the parasites are rare in 
the blood, but generally numerous in the immediate neighbourhood of 
the oedematous excoriations on the penis, so that, in coitus, they come 
into contact with the vaginal mucous membrane of a healthy mare, 
through which they are able to pass. 

Nervous symptoms may be only slightly noticeable (e.g. a dull and 
lethargic tendency towards the close of the illness), or they may be 
strongly in evidence, especially in Dourine, Mai de Caderas, and sleeping- 
sickness. In the two former, more or less general paralysis of the 
posterior part of the body frequently sets in ; Mai de Caderas of horses 
in South America is, indeed, often called " hip-paraplegia." In sleeping- 
sickness the Trypanosomes penetrate into the cerebro-spinal canal, and 
.can usually be found upon centrifugalising a sufficient quantity of the 

1 Holmes (Journ. Goinp. Pathol. xvii., 1904) and, more recently, Salvin-Moore and 
Breiiil (Ann. Trap. Med. i., 1907) consider that these resistant forms, for which the 
latter propose the term "latent bodies," are represented by certain of the amoeboid 
involution-forms described by Bradford and Plimmer, Laveran and Mesnil, and 
others (cf. p. 222). 



fluid; they have also been seen, in post-mortem examination, in the 
lateral ventricles of the brain. It is this invasion by the parasites of 
the nervous system that marks the transition of the case from one of 
" Trypanosoma-faveT " (while the parasites are confined to the blood) to 
one of sleeping-sickness. The results of the change are soon apparent 
in the onset of lassitude, tremor, and the other associated nervous 
symptoms which characterise this dreadful malady. 

Death from trypanosomosis is due either to weakness and emaciation 
(in chronic cases), or to blocking of the cerebral capillaries by the parasites 
(where these are abundant and the disease consequently acute and rapid), 
or to the disorganisation of the nervous system (paraplegic and sleeping- 
sickness forms). Laveran and Mesnil have expressed the opinion that 
some factor in addition to the presence of the parasites themselves 
especially when these are rare is requisite to explain the severe effects 
produced, and suggest that the Trypanosomes secrete a toxine. Neither 
they nor other investigators have, so far, been able to discover traces of 
any such substance. In post-mortem examination, the most obvious 
pathological feature is hypertrophy of the spleen, which may be very 
pronounced. The lymphatic glands in the neck, inguinal region, etc., 
are often greatly swollen and contain numerous parasites. 

The spleen and lymphatic glands are undoubtedly the organs 
which react most strongly 
to the parasites, and their 
enlarged condition is, prob- 
ably, to a great extent 
due to enhanced activity 
in elaborating blood -cor- 
puscles and leucocytes to 
cope with the enemy. In- 
gestion and dissolution of 
the Trypanosomes by 
phagocytes has frequently 
been observed (Fig. 6). 
It is very likely also that 
the haematopoetic organs 
eecrete some chemical or 
physiological substance 
which exerts a harmful 
action on the parasites, 
causing them to undergo 
involution and assume 
weird-looking "amoeboid" and "plasmodial" forms. 

In A the leucocyte is 

Fie. 6. 

Phagocytosis of T. lewisi. 

beginning to engulf the Trypanosome ; in B the latter 
is completely intracellular ; C-E show the gradual dis- 
solution of the parasite (p). n, nucleus of leucocyte ; 
c, ingested blood - corpuscles ; v, vacuoles remaining 
after their dissolution. (After Lav. and Mesn.) 


Trypanosomes vary greatly with regard to size ; even in one 
and the same species this variation is often noticeable, especially 



under different conditions of life. The well-known Trypanosoma 
rotatorium of frogs (Fig. 8, A and B) is, taking it all in all, one of the 
largest forms so far described. Its length 1 varies from 40 to 60 //, 
while its greatest width dorso-ventrally - is from 8 to 30 ^ ; in the 



FIG. 7. 

Representative Mammalian, Avian, and Reptilian Trypanosomes. A, Trypanosoma lewisi, 
after Bradf. and Plim. ; B, T. brucii, after Lav. and Mesn., x 2000 ; C, T. gambiense (blood, T.- 
fever), after Bruce and Nabarro ; D, T. equinum, after L. and M., x 2000; B, Trt/panomorpha 
(Trypanosoma) noctuae, after Schaud. ; F, Trypanosoma avium, after L. and M. ; G, T. hannae, 
after Hanna; H, T. (Spirochaeta) ziemanni, after Schaud. ; J, T. damoniae, after L. and M., 
x 2000. c.g, chromatoid grains ; v, vacuole ; l.s, longitudinal striation. 

very wide individuals breadth is gained more or less at the expense 
of length. Conversely, the human parasite, T. gambiense (Fig. 7, c), 
is one of the smallest forms, its average size being about 21 
to 23 ju, by 1 1 to 2 p.. The majority of Mammalian Trypanosomes 

1 The length is always inclusive of the flagellum, unless otherwise stated. 

2 Adopting Leger's convention, by which the convex side, bearing the undulating 
membrane, is distinguished as dorsal ; the measurements of width always include the 
undulating membrane. 


are fairly uniform in size (Fig. 7, A-D), the chief exceptions being 
T. theileri (Fig. 33), which is much larger than the rest, varying 
from 30 to 65 p in length ; and T. nanum, which is correspondingly 
minute, being only about 14 /A long. The Piscine forms, on the 
other hand, though possessing an equally great range, exhibit a 
more regular gradation. Starting with relatively small types, like 
T. remaki, var. parva, with a medium length of 30 /x, parasites of all 
sizes are to be met with up to T. granulosum (Fig. 8, K) and T. raiae 
(Fig. 38, B), which are among the longest Trypanosomes known, 
attaining a length of 80 //. 

There is equally great diversity of appearance. Typically the 
body is elongated and spindle-shaped ; it is generally more or less 
curved or falciform, and tends to be slightly compressed laterally. 
It may be, however, anything from extremely slender or vermiform 
(Figs. 8, K; 34) to thick-set and stumpy (Figs. 8, A; 35). More- 
over, apart from the fact that a full-grown adult, ready to divide, 
is in many cases much broader than a young adult (cf. T. lewisi, 
Fig. 20, B), considerable polymorphism also sometimes occurs (e.g. 
T. rotatorium, Figs. 8, A, B; 37). Again, there can be little or no 
doubt that, in some instances at any rate, sexual differentiation is 
expressed by more or less pronounced differences in appearance. 
In fact, from one reason and another, it is often practically impos- 
sible to define any one type within hard and fast limits, either of 
shape or size. 

In the biflagellate, Heteromastigine forms (Trypanoplasma and 
Trypanophis), the anterior extremity of the body is that, of course, 
from which spring the two flagella. With regard, however, to the 
correct orientation in the uniflagellate Trypanosomes (the genus 
Tri/panosoma sens, lat.) considerable uncertainty exists. For the 
present, 1 in order to avoid confusion, the two ends may be desig- 
nated as flagellate or flagellar, and non-flagellate or aflagellar 
respectively. On the whole, the flagellar extremity is fairly 
uniform and nearly always more or less tapering; but the non- 
flagellate end presents great variation, being, as Laveran and 
Mesnil point out, particularly plastic. On the one hand, it may 
be blunt and even rounded off at the tip, as in certain individuals 
of T. brucii (Fig. 7, B), T. equiperdum (Fig. 32, D), and in a Trypano- 
some of Senegambian birds (Fig. 35) ; on the other hand, it may 
be very long and attenuated, as in T. Jiannae (Fig. 7, G), occasionally 
simulating a true flagellum to a remarkable degree, this being the 
case in T. polyplectri. Between these two extremes all manner of 
intermediate conditions are to be found. An instance which well 
illustrates the great variability in one and the same form is seen in 

1 The whole question is so closely bound up with that of the phylogeny of the 
group that its consideration is best deferred until the two can be discussed together 
(see below, p. 246). 



Fio. 8. 

Representative Amphibian and Piscine Trypanosomes. A and B, Trypanosoma rotatorium, 
after Lav. and Mesn., x 1400; C, T. inopinatum, after Sergent, x 1000; D, T. karyozeukton, 

after L. and M., x 2000. h, clear zone or halo around kinetonucleus ; eh, chain of chromatic 
rodlets running between the two nuclei ; a.fl, anterior flagellum ; p.fl, posterior flagellum ; l.s, 
longitudinal striations or myonemes ; v, cytoplasmic vacuole. 

T. lewisi. Usually this parasite has a shai-p, pointed aflagellar end 
(Fig. 7, A) ; but in many of the individuals found in rats which 


have been recently infected (e.g. five or six days previously) this 
extremity is enormously drawn out and tapering like a whip (Fig. 
9). In such forms the flagellum is often very short. 

The two flagella, in Trypanoplasma and Trypanophis, are inserted 
into the body close to the anterior end (Fig. 8, F, G). They are 
quite separate from each other, and while one (that most anteriorly 
situated) is entirely free and directed forwards, the other at once 
turns backwards and is attached to the convex (dorsal) side of the 
body for the greater part of its length. This latter flagellum 
terminates in a shorter or longer free portion. 

The comparative degree of development of the two flagella in 
different cases is worth pointing out, since it is very instructive in 
a phylogenetic connection. Starting with Bodo lacertae, from a 
type similar to which the biflagellate forms may be derived, both 
flagella are of about equal total length, and the trailing one does 
not reach the posterior limit of the body. In Trypanophis grobbeni 
(Fig. 30) the posterior flagellum is more developed than the 
anterior one, and attached to the side of the body, but its free 
termination is very short. In Trypano- 
plasma borreli the anterior flagellum and 
the free portion of the posterior one are 
of equal length. Lastly, in T. cyprini 
the former is much shorter than the 
latter, and shows signs of reduction. 
From this condition to its disappearance 
is but a small step. 

In all other Trypanosomes there is 
only one flagellum, which is invariably 
attached to the body in the same manner 
as the posterior one of the biflagellate 
forms. The point of origin of the 
flagellum is generally near the non- 
flagellate end, but may vary consider- 
ably. Although there is usually a free 
continuation of the flagellum, it may be 
short or lacking (cf. Fig. 34). 

Along the dorsal side runs a char- 
acteristic fin-like expansion of the body, the undulating membrane 
This always begins proximally at the place where the attached 
flagellum emerges from the body ; and its free edge is really con- 
stituted by the latter, which forms a flagellar border, more or less 
sinuous in outline. The membrane may be only narrow, and 
chiefly discernible by its well-marked border (Figs. 7, A, G ; 8, c), 
or it may be well developed and sometimes thrown into broad folds 
or pleats (Figs. 7, r ; 8, A, B). Distally the membrane thins away 
.concurrently with the body. 

T. lewisi, from a 
rat five days after 
inoculation to show 
the remarkably long 
aflagellarend. (From 
an original drawing 
kindly lent by Dr. 
J. D. Thomson.) 


Minute Structure. The body appears to lack any distinct 
limiting membrane or 1 cuticle. A differentiation of the peripheral 
cytoplasm in the form of an ectoplasmic layer, the so-called " peri- 
plast," has only been definitely described in a few cases (Prowazek 
[68], Wasielewsky and Senn [86]). Nevertheless, it is probable 
that in most Trypanosomes there is such a layer, although it may 
be, in some forms, only poorly developed around the body generally. 
The undulating membrane, however, is certainly largely, if not 
entirely an ectoplasmic development. This is usually much clearer 
and more hyaline in appearance than the general cytoplasm. The 
latter is finely granular or alveolar in character, though its exact 
degree of coarseness and density varies in different forms, some- 
times even in different parts of the same individual. The cyto- 
plasm of male forms is in general clearer and less granular than 
that of female ones. The cytoplasm in T. mega and T. karyozeiitton 
is rather unusual in structure. In the third of the body on the 
aflagellar side of the nucleus, it is very loose and spongy ; in the 
other two -thirds, it is arranged in alternating light and dark, 
densely-staining bands (" hyaloplasm " and " spongioplasm "), run- 
ning more or less longitudinally. 

Cytoplasmic inclusions of one kind or another are often to be 
found. In many Trypanosomes, deeply -staining granules occur, 
which vary greatly in number and size. These granules appear 
to be chiefly distributed, as a rule, in the flagellate half of the 
body (Fig. 7, B, D). They are of a chromatoid nature, and probably 
derived from the nucleus (see Lignieres [54]). In Trypanophis there 
are one or two rows of highly refractive, yellowish inclusions run- 
ning the length of the body (Fig. 30). It is thought that these 
represent collections of fatty or oily substances. In certain forms, 
a well-defined, usually oval vacuole is often, though not constantly 
present, situated at a varying distance from the aflagellar end (Figs. 
7, C, G ; 8, F). There is no reason to doubt that this vacuole is a 
normal cell-constituent, for it has been observed in parasites in their 
natural (tolerant) hosts under quite normal conditions. 

Until recently, very little was known with regard to the 
details of nuclear structure. A Trypanosome was merely described 
as possessing an unmistakable nucleus, and also a small deeply- 
staining element of uncertain significance, situated at the root of 
the flagellum, and termed variously " blepharoplast," centrosome, 
or micronucleus. It is to Schaudinn that we are indebted for the 
revelation of the essential nuclear nature of the latter organella, 
its intimate connection with the larger nucleus and the complexity 
and differentiation which the whole nuclear apparatus may 
exhibit. Since then several workers have brought forward 
observations relating to one point or another, which, taken alto- 
gether, suggest strongly that the nuclear organisation of Trypano- 



somes in general is based upon a plan fundamentally similar to 
that described by Schaudinn in the case of his Avian parasite, 
Trypanomorpha noduae. The development and ultimate constitution 
of the nuclear apparatus in this type are as follows : 

The account may be commenced with the condition found in an 
indifferent ookinete or individual which will become an indifferent (non- 
sexual) Trypanosome. Here a single, large compound or double nucleus 
is present, consisting of an external portion and of rtn internal, central 

FIG. 10. 

Development of an indifferent Try- 
panosome from an ookinete of indif- 
ferent character. (After Schaudinn.) 
t.chr, trophonuclear chromosome ; 
K.chr, kinetonuclear chromosome ; c, 
centrosomic granule ; a.s, first axial 
spindle ; o.s 2 , a.s 3, second and third 
spindle ; t. trophonucleus ; k, kineto- 
nucleus ; fc.e, kinetonuclear centro- 
soine; t.f, trophonuclear centrosome ; 
m, myonemes ; /.';, flagelliir border of 
undulating membrane (third axial 
spindle) ; u 3 , its proximal centrosome. 

portion (Fig. 10, A). The former has eight distinct, peripherally situated 
chromosomes ; the latter also has eight separate chromosomes. In the 
centre of all is a well-marked centrosomic granule (c). The first change 
takes place by the inner body becoming amoeboid and giving up its 
material to the outer, surrounding part (B). The result is that the eight 
chromatic elements of the former become united, by the aid of the plasti- 
noid basis present, with those of the latter, leaving the above-mentioned 
grain in the middle. This granule divides in a dumb-bell-like manner, 
producing a small axial spindle (c, a.s.), around which the eight compound 
chromosomes arrange themselves. These next split, and the halves pass 
to either end, forming a diaster which is markedly heteropolar. The 


right (or dorsal) half is perceptibly smaller, but denser and more deeply 
staining than the other. In this manner, therefore, two distinct nuclear 
bodies are formed, of different size and character. They remain connected 
together by a fine achromatic thread, representing the original central 
spindle, which ends in a small granule near the centre of each. The 
larger nucleus, lying nearer the middle of the body, rapidly reconstitutes 
itself and enters upon a resting-phase. This nucleus regulates the trophic 
functions of the cell, for which reason we have proposed (3) for it the 
name trophonucleus. 

Meanwhile, the other, smaller nucleus proceeds to give rise to the 
characteristic locomotor apparatus of the Trypanosome. It passes forwards 
slightly and takes up a position at the periphery of the endoplasm, lying 
indeed against the limiting ectoplasm. Its centrosome divides again in 
a similar manner, forming another axial spindle (E, a.s 2 ) at right angles, 
as before, to the length of the parasite. Another heteropolar division 
next takes place, giving rise to two daughter-nuclei ; these also remain 
connected together by the drawn-out central spindle, which join the two 
centrosomic granules. The peripheral daughter-nucleus, situated almost 
in the ectoplasm, forms yet another spindle (F, a.s 3 ), whose axis is now, 
however, longitudinal. This assumes large proportions and spreads 
forward to the anterior end of the body, the whole lying in the ectoplasm, 
which becomes greatly developed to form the undulating membrane. 
The central spindle becomes excentric in position and sinuous in outline, 
and strengthens, or rather itself constitutes, the free edge of the membrane, 
forming a -flagellar border to it (H, /.&). A supporting framework is 
formed by eight myonemes, representing the eight elongated daughter- 
chromosomes, four of which are arranged on each lateral surface. The 
flagellar spindle does not stop on reaching the anterior end of the body, 
but continues to elongate, drawing out with it the undulating membrane, 
which narrows and finally thins away. The myonemes then unite with 
the spindle to form the free flagellum, the centrosome at the distal end 
disappearing as such, but that at the basal or proximal end persisting (c). 
By this time the other daughter-nucleus has become rounded off as the 
kinetonucleus (k), which regulates all the kinetic activities of the parasite ; 
it remains connected with the locomotor apparatus by a delicate thread, 
representing the second axial spindle. 1 

According to Prowazek's recent investigations, the same type of 
nuclear structure is also shown by two Mammalian forms, T. lewisi 
and T. brucii ; indeed, it is maintained that the system of axial 
spindles produced by successive divisions of the karyocentrosome 

1 Two other points bearing on the view that the flagellum represents the greatly 
elongated axial spindle of a nuclear division may be noted. In Trypanosoma 
johnstoni, where there is no free portion of the flagellum, this terminates (at the 
limit of the cytoplasm) in a small deeply-staining granule (Fig. 34), perhaps com- 
parable to the distal centrosome of such a spindle. Again, Miss Robertson (72) 
sums up her account of the origin of the flagella in the development of the flagellate 
form from the rounded, aflagellar type in the case of her leech -Trypanosome by 
saying, "the two flagella appear to be developed from a pair of arrested mitotic 
figures developed out of the distal of the two segments into which the original 
kinetonucleus divides." 



is even more elaborate in the former parasite than in the case just 
described. Further evidence in support of Schaudinn's view of 
the intimate relation and correspondence between the two nuclear 
organellae is furnished by L6ger (50), who has observed, in 
"ookinetes" of T. barbatiilae (see under "Life-Cycle"), heteropolar 
division of a single large nucleus, doubtless leading to the forma- 
tion of tropho- and kinetonucleus ; and by Bradford and Plimmer 
(6), who have observed the latter element (" micronucleus ") a given 
off from the larger nucleus in T. brucii. Perhaps the most striking 
confirmation of the essential nuclear character of the kinetonucleus 
is afforded, however, by a comparison of this organ ella in Trypano- 
plasma borreli, where it is particularly large, and like a nucleus ; in 
fact, it was originally regarded as the nucleus (trophonucleus) of 

FIG. 11. 

Trypanoplauma lorreli, Lav. and Mesn. a.f, anterior flagellum ; p.f, posterior flagellum ; m, 
undulating membrane ; T, trophonucleus ; K, kinetonucleus ;' /, fibril (myoneme) ; c, centre- 
somic granule at base of flagellum. (After Leger.) 

this parasite. Moreover, in addition to the kinetonucleus, and 
immediately in front of it, two centrosomic granules can be 
distinctly seen, one at the base of each flagellum (shown clearly in 
Lager's figures, Fig. 11, B, c). In Tnjpaiwsoma also, in many cases, 
the root of the flagellum is not actually connected with the kineto- 
nucleus, but terminates before reaching it in an unmistakable 
granule, which we have found to stain much darker than the 
flagellum. Lastly, in this connection the writer has been very kindly 
permitted by Prof. Minchin to make use of two figures of his (about 
to be published) of Trypanosoma grayi undergoing division, in which 
centrosomic granules, associated with the kinetonuclei, are clearly 

1 It is necessary to point out that the kinetonucleus is not a "micronucleus," 
in the sense in which this term is always used as applying to that body in the 
Tnfusoria. In the Trypanosomes both nuclei are equally essential and functional, 
in somatic life as well as in sexual reproduction. 


shown (Fig. 12). An additional feature of interest is the presence 
of a well-developed axial spindle, still connecting the two tropho- 
nuclei (which have divided last), and ending in a granule inside 
each, which is doubtless the trophonuclear centrosome. In other 
cases (e.g. T. remaki, Trypanoplasma borreli, Trypanopliis) as well, a 
large, distinct granule has been described in the centre of the nucleus, 
which very probably represents the trophonuclear centrosome 
(karyocentrosome). To sum up, the above facts leave little reason to 
doubt (a) that the kinetonucleus of a Trypanosome is not merely 
an extranuclear centrosome, 1 but a true nucleus, homologous with 
and equivalent to the trophonucleus, the two being specialised for 
different functions ; and (b), that distinct centrosomes are associated 
with both nuclei, the trophonucleus possess- 
ing an intranuclear one, while in connection 
with the kinetonucleus there is an extra- 
nuclear one (at the base of the flagellum) 
and perhaps also an intranuclear one (accord- 
ing to Schaudinn). 

Both nuclei vary greatly with regard 
to their position in the body, in different 
forms, as will be seen on comparing the 
figures given. As a rule, the trophonucleus 
P IG . 12. lies somewhere near the middle of the body, 

Trypanosorna grayi, dividing, and the kinetonucleus near the aflagellar 
nlnTdrlwtfti So^SS end, being farther from it in proportion as 
somic granules are seen one the extremity is tapering. In some cases, 

above each kinetonucleus. ' a . . . ' 

however, at all events during certain periods 

of life, the two nuclei lie close together centrally, at times being 
actually in contact (cf. T. inopinatum, Fig. 8, C ; T. " iransvaaliense," 
Fig. 33 ; T. rotatorium, Fig. 8, B; and T. lewisi, young forms, Fig. 
21, E). The trophonucleus is generally ovoid in shape, the longer 
axis being longitudinal, but in the Trypanosome described by 
Button and Todd from Senegambian birds, and also in T. hannae, 
the long axis is transverse to that of the body (Figs. 7, G; 35). 
As regards its minute structure, the trophonucleus appears generally 
to consist of an aggregation of chromatin grains embedded in a 
plastin-like matrix. No mention is usually made of a nuclear 
membrane or reticulum. In his account of Trypcmoplasma borreli, 
it may be noted, Le"ger (49) has described eight dumb-bell-shaped 
chromosomes. An unusual appearance of the trophonucleus has 
been observed in one or two instances (T. brucii, Stuhlmann and 
Miss Kobertson ; T. raiae, in the leech, Miss Robertson). In these, 

1 Salvin-Moore and Breinl, in their account of the " cytology of the Trypanosomes " 
(Ann. Trap. Med., Liverpool, 1907), continue so to regard this organella, in spite of 
all the evidence to the contrary, much of which (e.g. that furnished by Trypanoplasma) 
they entirely overlook. 


this organella is very much elongated, and the chrottiatin is arranged 
in the form of a ladder of parallel rods or pairs of granules (chromo- 
somes ?). There is not much to note with regard to the kineto- 
nucleus. In a solitary instance, namely, T. equinum, it is extremely 
minute and difficult to distinguish ; it appears as a dot-like thicken- 
ing at the root of the flagellum (Fig. 7, r>). In this case, the 
organella has apparently become reduced. 

The occurrence of prominent myonemes in the undulating 
membrane of Trypanomorpha, and their nuclear origin (as " mantle- 
fibrils "), has been already described. According to Prowazek 
{I.e.), a similar development occurs in both T. lewisi and T. brucii ; 
here the myonemes lie in the general ectoplasm of the body, f oni- 
on each side, but they are very delicate and difficult to make out. 
In two or three other parasites longitudinal striations, comparable 
to muscle-fibrillae, have been observed ; nothing is known, how- 
ever, about their origin. Thus in Trypanoplasma borreli there are 
two, one on each side of the body, which start in front and run 
backwards more than half-way, finally joining ventrally (Fig. 11, 
c, /). Again, in Trypanosoma, soleae (Fig. 8, j), the ribbed forms of 
T. rotatorium (Fig. 37, A), and in T. avium (according to Novy and 
M'Neal), myoneme striations are well marked. 


A. Movement. In general, Trypanosomes are extremely active 
.organisms. According to the manner in which they are produced, 
two kinds of movement can be distinguished : (1) displacement of 
the body, usually rapid ; and (2) creeping and pushing movements, 
by means of flexion, extension and contraction of the body, etc. 
The latter kind are brought about, in all probability, by the super- 
ficial myonemes mentioned above ; they are, in fact, often comparable 
to " euglenoid " movements (cf. the flexion movements of sporozoites). 
In all such cases, it is important to note, the non-flagellate end 
moves first. 

In active movements of displacement, the flagellar extremity 
generally leads the way. The motion may be very rapid and 
relatively considerable, as in T. lewisi ; or sluggish and inconsider- 
able, as in T. brucii, whose powers of active displacement appear 
slight or else little used. There is some difference of opinion as 
to whether the undulating membrane or the flagellum plays the 
principal part in this locomotion. The flagellum doubtless acts to 
a certain extent as a tractellum, especially in cases of very rapid 
movement. In Trypanoplasma, in which, of course, the anterior 
end goes first, the principal organella concerned, according to Ledger 
(I.e.), is the undulating membrane, whose rapid vibrations produce 
.quickly succeeding waves, running backwards. The oscillations 


may be continued into the posterior flagellum, which then acts as a 
pulsellum ; Leger thinks, however, that this flagellum functions 
chiefly as a rudder (Schleppgeissel). The anterior flagellum is not 
greatly, if at all, concerned in the movement. 

All Trypanosomes undergo, more or less continually, a vibratile 
or undulatory motion of the membrane, which may take place in 
either direction. Among the elongated Piscine forms, movements 
of contortion are much in evidence, the body being frequently 
coiled up on itself. In many Trypanosomes, again, especially the 
more spirochaetiform ones, the membrane appears spirally wound 
round the body, this being due to a more or less pronounced 
torsion of the latter, which gives the animals a corkscrew-like motion. 

B. Agglomeration. This characteristic phenomenon of Trypano- 
somes occurs chiefly or only upon the advent of unfavourable 
biological conditions in the surrounding medium. In the normal 
blood or other humour of Vertebrate hosts agglomeration has only 
been observed in one or two cases, when it has been termed auto- 
agglomeration. Agglomeration is readily brought about artificially 
in various ways ; e.g. when drawn blood containing the parasites is- 
kept for some time at a low temperature ; when sera of other 
animals, especially of animals which have been once or twice inocu- 
lated with the particular Trypanosome, are added to fresh blood ; 
or by the addition of chemical solutions. 1 

Agglomeration generally commences by two Trypanosomes 
coming together and joining (Fig. 14, A) ; and the union may some- 
times remain only binary. In most cases, however, the agglomera- 
tion progresses rapidly, a number of parasites collecting round a 
common centre and forming a multiple union or rosette (Figs. 13 ; 
14, B). Such a cluster or rosette is known as a primary agglomera- 
tion, and may consist of as many as a hundred individuals ; some- 
times the rosettes themselves become grouped together to form large 
tangled masses. In a natural (as opposed to an artificial) medium r 
agglomeration of a particular form of Trypanosome takes place, 
typically, by the same extremity. In Trypanomofpha noctuae, accord- 
ing to Schaudinn, this is the flagellate (anterior) end ; i.e. the 
parasites unite with the flagella pointing towards the centre (Fig. 1 3). 
In Trypanosoma, on the other hand, the union is by means of the 
aflagellar end. 2 

1 For fuller details the reader is referred to the works of Laveran and Mesnil 
(37, 43), Lignieres (54), Thiroux (83), and others. 

2 In artificial cultures, clusters are frequently observed in which the arrangement 
of the parasites is not constant, even in the same species ; that is to say, some- 
times the Trypanosomes have their flagella at the periphery, while at others the 
flagella are centrally directed. It appears, however, that two entirely different pro- 
cesses are concerned. In some cases, at any rate, those clusters which have the 
flagella pointing centrally are instances not of agglomeration, but of rapid successive 
division, where the parasites remain more or less in contact and form large colonies. 
This has been well brought out by Novy and M'Neal (62, 63), Thiroux, and others. 



This peculiar feature of Trypanosomes differs in one or two 
important respects from the somewhat similar phenomenon of 
agglutination in Bacteria. The Trypanosomes do not in the 
slightest lose their mobility during the process. Each individual 
continues active movements, its flagellum lashing away at the 
periphery, and appears to be making strenuous endeavours to escape. 
Again, a rosette is able to become disagglomerated ; a bacterial 
cluster or agglutination, on the other hand, is never dissolved. 
Disagglomeration is appar- 
ently in consequence of the 
retention of the power of 
movement by the parasites. 
Sometimes all the indi- 
viduals, apparently quite 
unaltered morphologically, 

FIG. 13. 

Agglomerated cluster of 
male forms of Trypanomor- 
pha noctuae in the intestine 
of the gnat. (After Schau- 

FIG. 14. 

A, binary union or agglomeration of T. 
lewisi. B, primary rosette of the same parasite. 
(After L. and M.) 

become thus dispersed. At other times disagglomeration is only 
partial, a certain number of the more feeble Trypanosomes remaining 
together and slowly dying. If the agglomerating serum is very 
powerful, however, or if the biological conditions remain unfavour- 
able, the rosette does not break up and the parasites at length 
die off. 

The significance of the process has yet to be ascertained. By 
some it is regarded as a purely involuntary proceeding on the part 
of the parasites, and brought about more or less mechanically. A 
suggestion put forward by Lignieres (54) is not without interest, 
particularly when the recent work of Calkins on the essential 
meaning of fertilisation is borne in mind. This author considers it 
quite probable that, as a result of the close intimacy, a molecular 
interchange goes on between the associated individuals, which may 
have a stimulating or recuperative value. 

C. Abnormal and Involution Forms. Involution and degenerative 
phases of Trypanosomes have received attention and acquired an 



importance altogether undeserved, owing chiefly to the fact that 
many of these parasites have been studied, so far, only in strange 
and unaccustomed hosts hosts to which they are unadapted, and 
for which they, on their part, prove markedly pathogenic. 

Trypanosomes appear to be, in most cases, able to support, for a 
longer or shorter period, unfavourable conditions of environment, 
whether due to the reaction of the host itself or to the transference 
of the parasites to a strange medium. Sooner or later, however, 
the organisms feel the effects of such changed circumstances and 

Flo. 15. 

Involution and degeneration forms of different Trypanosomes. A-E, T. gamble-use (A, C, and 
B after Bruce and Nabarro ; B and D after Castellani). P, K-P, T. brucii (F after Br. and 
PI. ; K-P after L. and M.). G-J, Q and R, T. equinum (after Lignieres.) 8, T. brucii, plas- 
morlial mass, from spleen pulp (after Br. and PI.). 

become markedly altered. The strange forms and appearances 
frequently described are probably for the most part l abnormal ; i.e. 
they do not represent phases in the typical life-cycle, but are vary- 
ing stages in a process of degeneration. Nevertheless, it by no 
means follows that the parasites rapidly die off. On the contrary, 
many of these involution-forms, on entering the blood of a fresh 
host, are able to infect it, though they may even have been kept for 
some time in artificial surroundings. 

The course which involution takes varies in different cases, but 
the process generally follows one or another of three lines, which 

1 See footnote to p. 222. 



may occasionally be met with in combination in any given abnormal 
form. (a) Chromatolysis. Here there is either a more or less 
complete loss by the nucleus (usually the trophonucleus) of its 
chromatic constituents, which pass out into the cytoplasm leaving 
only a faintly staining plastinoid basis (Fig. 15, A) ; or else direct 
fragmentation of the nucleus occurs (F-j). 1 (b) Vacuolisation. The 
frequent presence of a vacuole in many Trypanosomes, which is 


FIG. 16. 

Involution and degeneration forms (continued). A-C, T. bntcii, after Br. and PI. ; D-G, T. 
iiomiiiense, after Castellani ; H, T, briicii, after Martini ; J, K, T. equinum, after Voges ; L, T. 
brucii, agglomeration-cluster, commencing to form a plasmodium, after I3r. and PI. 

probably to be regarded as a normal cell-organella, has been men- 
tioned above. The first indication of abnormality in this direction is 
perhaps afforded when the vacuole increases very greatly in size (Figs. 

15, E ; 16, E). Other, irregular ones may appear in the cytoplasm, 
when the involution becomes pronounced in character (Figs. 15, C; 

16, G). (c) Change of form. This is, from the weird forms often 
resulting, the most obvious line of involution. Alteration in shape is 
generally accompanied by an increasing loss of mobility. In the 

1 In certain of these cases it is possible that something in the nature of chrom- 
idial formation may be going on, leading to nuclear readjustment. 


case of single forms the body becomes stumpy (Fig. 15, C-E), losing 
almost entirely its trypaniform shape, and ends by being ovoid or 
like a ball (c, H, L) ; l the flagellum is limp and inactive and partially 
coiled up (j). In other cases, quite irregular multiplication occurs, 
accompanied by incomplete cytoplasmic division, leading to the forma- 
tion of distorted multinucleate and multiflagellate bodies (Fig. 16, 
A G). Lastly, various fusion -forms may be met with, masses of 
Trypanosomes gradually losing their distinctness and constituting 
large plasmodia (Figs. 16, L; 15, s), made up of a great number of 
nuclei embedded in a common cytoplasmic matrix. 

If the organisms remain subjected to the unfavourable influences, 
or if involution has reached too advanced a stage, death and dis- 
integration result. The cytoplasm is the first to disappear, becoming 
hyaline and colourless, and refusing to stain up. The nucleus 
rapidly follows suit. The most resistant elements are the kineto- 
nucleus and flagellum, which may persist long after other traces of the 
organism have vanished (Fig. 15, p), the former as a little thickening 
at one extremity of the latter ; sometimes the flagellum alone is left. 


Binary longitudinal fission is, probably, of universal occurrence, 
and appears to be the usual method of multiplication ; though 
Trypanosoma lemsi, at any rate, possesses another method in 
addition, namely, rosette -like segmentation. 

The process of fission begins with the division of the nuclear 
and locomotor apparatus, but the actual order of division of these 
different organellae appears to be very inconstant and variable. 
As a rule, the kinetonucleus leads the way, but sometimes the 
trophonucleus may. The duplication of the flagellum begins at 
its proximal end, that which is in relation with the kinetonucleus. 
Until lately the process has always been considered as an actual 
longitudinal splitting of the flagellum, following upon the separation 
of the two daughter-kinetonuclei. Now and again examples are 
met with in which the duplication of the flagella has taken place 
before the kinetonucleus has divided. It seems probable that it 
is really the division of the kinetonuclear centrosome which is the 
essential prelude to the division of the locomotor apparatus. This 
flagellar splitting has been described either as extending to the 
distal end of the undulating membrane, after which the two halves 
separate (Fig. 17, c), or as being practically limited to the root- 

1 It is here, if anywhere, that there might be a possibility of regarding as involution- 
forms phases which really belong to the normal life-cycle ; e.g. rounded-off, resting 
phases (cf. the " resistant forms " of Holmes and others). In such, however, the 
flagellum would doubtless be absent, while the nuclear elements and cytoplasm would 
be as usual ; in fact, the parasites might well show a resemblance to the Leishman- 
Donovan bodies (cf. pp. 255 et seq.). 



portion, which becomes thickened and then divides, one half break- 
ing away as a new, short flagellum, whose further growth is basal 
and centrifugal (Fig. 20, D). Schaudinn found, however, that in 

A. C 

FIG. 17. 
Stages in binary longitudinal fission of T. brucii. (After Lav. and Mesn.) 

Trypanomorphi noctuae the whole of the flagellum, etc., is developed 
quite independently from the daughter-kinetonucleus, and laid 
down alongside and parallel with the old locomotor apparatus ; 
moreover, Prowazek (I.e.) and also M'Neal (56) maintain that the 
same is the case in T. lewisi. Nevertheless, in many cases it seems 
hardly possible to doubt that there is actual splitting of the 
flagellum ; where, for in- 
stance, the two new flagella 
of the proximal part of the 
body appear to actually 
join arid continue as one, 
yet undivided flagellum 
(as seen in Fig. 17, A 
and B). Again, even 
where a daughter-flagellum 
is separate from the main 
one, the course of the two 
is often so exactly parallel 
that their origin by longi- 
tudinal fission is highly 

So far, we have not much knowledge with regard to the 
cytological details of nuclear division. Prowazek has given a 
description of the process in T. brucii. The kinetonucleus becomes 
thickened and spindle -like (Fig. 18, A). Subsequently it becomes 

Flo. 18. 

Details in the nuclear division of T. brucii. 
(After Prowazek.) 



dumb -bell -shaped, after which the two halves become farther 
separated, remaining connected only by a short thread (B). 
The chromatin of the trophonucleus is arranged in eight rather 
elongated chromosomes, which next begin to divide in a similar 
dumb-bell-like manner (Fig. 18, c). The trophonuclear karyosome 
(karyocentrosome) has frequently divided by this time ; but in 
one instance Prowazek observed it much drawn out and functioning 
as an intranuclear division centre (n), the chromatin having 
become aggregated around its ends. 

In her account of T. raiae in Pontobdella Miss Robertson (I.e.) 
has gone at length into the question of nuclear division. The 
kinetonucleus appears to divide by a simple kind of mitosis though 

FIG. 19. 

A-D, stages in the binary longitudinal tission of 7'. r</ inn m ; K, multiple fission in the same 
parasite ; F and G, binary and multiple division in T. cfiuiperdum. (After Lignieres.) 

the details are extremely obscure. The trophonuclear division also 
takes place by a simple kind of mitosis, but shows a well-defined 
achromatic figure (comparable to a series of axial fibrils). This 
probably arises from the trophonuclear centrosome. The figures 
showing the later phases of the process convey quite the same idea 
as does Fig. 12 of T. grayi. In fact, this case also appears to 
conform to the same general plan as those above described. 

The division of the cytoplasm takes place last. In the great 
majority of forms this is equal or sub-equal, and the two resulting 
daughter-Trypanosomes are of approximately the same size (Figs. 
17 ; 19, c). Although the cytoplasmic fission usually begins at the 
flagellar end, it may start at the opposite extremity (cf. Fig. 19, D). 
In some instances (Fig. 19, E and G) the longitudinal fission is 


multiple, the original individual giving rise, simultaneously, to three 
or four descendants. 

T. lewisi differs from most Trypanosomes in that the cytoplasm 
generally * divides in a very unequal manner (Fig. 20). Indeed, 
the process is more comparable to budding, since the larger or 
parent individual may produce, successively, more than one 

FIG. 20. 

Unequal division in T. lewisi. m, parent-individual ; <7, daughter-individual ; rf 1 , daughter- 
individual dividing, x 2000. (A-E after Lav. and Mesn. ; F after Wasielewsky and Senn.) 

daughter-individual ; moreover, the progeny may themselves sub- 
divide before separating, the whole family remaining connected 
together by the non-flagellate end (Fig. 20, E and F). In this type 
of division, it may be noted, the kinetonucleus comes to lie alongside 
the trophonucleus, or even passes to the other side of it (i.e. nearer 
the flagellar end). This method of division forms, as it were, a 

1 Swingle (81) lias recently found that T. lewisi may also divide by equal binary 
fission ; and in such cases the two flagella may lie on opposite sides of the body. 




transition between binary fission and the other characteristic method 
of T. lewisi, namely, segmentation or rosette-formation (Fig. 21). 
The chief difference is that, in the latter, no parent-individual is 
recognisable, the segmentation being equal and giving rise to a 
rosette of equal daughter-Trypanosomes. 

The small parasites resulting from either of these modes of 
division (Fig. 21, E) differ from typical adults by their stumpy, pyri- 
form shape, the position of the kinetonueleus near the fiagellar end 
of the body, and the absence, during the first part of their youth, 
of an undulating membrane. At this period they have a somewhat 
Herpetomonas-like aspect. These young individuals can them- 

A-D, segmentation (rosette-formation) in T. lewisi ; in C nuclear division lias finished and 
the daughter-nuclei (of both kinds) have taken up a superficial position, while the cytoplasm 
lias become lobulated at the periphery, prior to the formation of the daughter-Trypanosomes. 
E, daughter-individual ; F, one dividing, x 1750. (After L. and M.) 

selves multiply by equal binary fission, giving rise to little 
fusiform parasites ; and, with growth, these gradually assume the 
adult appearance. 


It may be safely said that this remains, even to-day, one of the 
most difficult and most debated questions among the whole of the 
Protozoa, in spite of the amount of work, of one kind or another, 
which has been contributed to the subject during the last few 
years. When the present writer compiled his Review of the 
Haemoflagellates (3) some years ago, Schaudinn's remarkable 
observations had been, to all appearance, amply corroborated in 
various directions by the testimony of the Sergents (77), Billet 
(4, 5), Brumpt (9), Leger (50), and Rogers (94) ; in short, the 


whole trend of research pointed at the time to a very complex 
life-cycle of the Haemoflagellates and to a close connection with 
the Haemosporidia. Since then, however, owing in a great 
measure to the work of Novy and M'Neal on the Trypanosomes of 
birds (62) and of mosquitoes (63), the results obtained by 
Schaudinn have become, to a large extent, discredited ; these 
authors maintaining that they are capable of a quite different 
interpretation. Moreover, influenced by their work on Insectan 
Flagellates, Novy and his colleagues have gone to the other 
extreme and expressed their belief not merely that Haemoflagellates 
and Haemosporidia are entirely distinct, but also that the Trypano- 
somes of Vertebrates do not undergo any true development or part 
of their life-cycle in the Insectan host. This latter view, at all 
events, is, AVC think, shown to be incorrect by the most recent 
research, which, as above mentioned, seems all in favour of an 
alternate, Invertebrate host, one of the most important indications 
being with regard to the specificity of the latter a point of the 
utmost consequence in its bearing upon investigations of this kind. 
Leaving aside for the moment a consideration of Schaudinn's 
celebrated memoir, it Avill be best to give first a brief account of 
the results obtained in this connection by different prominent 
researchers, to other aspects of whose work reference has been 
previously made. 

Dealing first with Trypanosomes of cold-blooded Vertebrates, 
the earliest important observations are those of Le"ger (50), relating 
to Trypanoplasma varium and Tri/panosoma barbatulae of the loach. 
Leger distinguishes ordinary ("indifferent") and larger, more 
granular (probably female) forms of the Trypanoplasma in the 
blood of the fish. When a leech (Hemiclepsis sp.) was allowed to 
suck blood containing only these parasites, which thereupon passed 
into its stomach, the indifferent forms degenerated and perished, 
while the female ones became massive and showed nuclear changes, 
preparatory, Leger thinks, to a sexual process. At any rate, after 
some days, the intestine of the leech contained numerous little 
narrow Trypanoplasms, of which some, very filiform, perhaps 
represented male forms, while others possessed a kind of beak or 
rostrum in place of the anterior flagellum, which made them 
resemble Trypanosomes. The development of Trypanosoma bar- 
batulae in another leech (Piscicola) showed a certain amount of 
agreement with that described by Schaudinn in the case of his 
Avian Trypanosome in the gnat (Culex). Eighteen hours after 
the leech had fed on blood containing exclusively T. barbatulae, 
pyriform bodies lacking a flagellum (" ookinetes ") were found in 
the intestinal contents. Some of these had a single large nucleus 
ii.e, a compound nucleus) ; others had two nuclei, one smaller than 


the other. Four days later the intestine contained numerous 
Trypanosmes which could be readily distinguished as belonging to 
one of Schaudinn's three types namely, indifferent, male, or female. 
The male forms are very elongated and slender, provided with a 
minute rostrum at the aflagellar end, and with a well -developed 
flagellum at the opposite extremity, which renders them extremely 
active ; they also creep or crawl with the rostrum in front. Their 
cytoplasm is very clear and usually lacks granulations. Female 
forms, on the contrary, are large and broad, with deeply staining, 
usually granular cytoplasm ; the flagellum is only feebly developed 
and the movement is sluggish. The indifferent individuals occupy 
in most respects an intermediate position between the other two 
types. A point of importance is that the kinetonucleus frequently 
lies in about the middle of the body, and may be close to the 
trophonucleus. There can be no doubt, it may be here remarked, 
that these different sets of forms are of regular occurrence in, at 
any rate, certain Trypanosomes. Since Schaudinn first described 
them several observers have recognised them, in some instances in 
the Vertebrate host, but always more sharply differentiated in the 
Invertebrate. In general, the three types show the same charac- 
teristics as noticed in the case of T. barlatulae. The indifferent 
forms, Leger states, underwent active multiplication, by equal 
fission ; those females which divided did so very unequally, by 
a process somewhat like budding. The manner and form in which 
the parasites passed back into the fish were not ascertained. 

'In his valuable contributions on the behaviour of Piscine 
Trypanosomes in leeches, Brumpt (11) has noted developmental 
phases of T. granulosum of the eel in Hemidepsis. Some hours 
after arrival in the stomach of the leech, all the parasites become 
pyriform, and by the position of the kinetonucleus close to the 
trophonucleus recall Lager's Crithidia-typQ (see below). By active 
multiplication, an enormous number of little forms are produced, 
which by the end of forty-eight hours have nearly all passed into 
the intestine. Here they rapidly become elongated, assuming a 
Herpetomonad-form, which may be retained for several months. 
Some, however, by the end of seventy-two hours, have given rise to 
true Trypanosoma-forms, with typical undulating membrane, which 
pass forwards towards the stomach, and may be found accumulated 
in the foremost stomach-coeca and in the proboscis-sheath by the 
fifth day. These are the forms which are inoculated into the eel, 
becoming by simple elongation ordinary T. granulosum again. 

Miss Robertson has published (72) some interesting observations 
on a Trypanosome met with in Pontobdella muricata, which she 
regards as T. raiae. This view is rendered extremely probable from 
the fact that Brumpt (10) has found that T. raiae does develop in 
Pontobdella. According to both authors the earliest phases occurring 


are rounded forms with both nuclei but no locomotor apparatus 
comparable to ookinetes, in short (cf. T. barbatulae above). These 
individuals, says Miss Eobertson, which divide in this condition 
fairly actively, gradually disappear from the crop and are found 
only in the intestine. Here they develop a locomotor apparatus, 
but persist for some time in a Crithidia-]\ke form ; they are of 
varying size and may be very small. Later on, these individuals 
take on a more or less typical Trypanosome-like, or, as we have 
previously termed it, trypaniform character, with the kinetonucleus 
in the aflagellar half of the body, though its actual position varies 
greatly. These trypaniform individuals are of two main types, 
which appear, however, to be connected by intermediate grades. 
One kind is relatively very broad, with a relatively small kineto- 
nucleus, but usually with a fairly long flagellum. The other type 
is a long slender Trypanosome, with a large kinetonucleus, but the 
free flagellum is not, as a rule, very long. The constitution of the 
trophonucleus presents an unusual condition ; it is very much 
drawn out, and the chromatin is arranged in a number of transverse 
rods or bars (perhaps comparable to chromosomes) arranged more 
or less parallel, like a ladder (cf. author's note on T. brucii above, 
p. 216). About the middle of digestion, these Trypanosomes occur 
chiefly in the intestine, but also in the crop, often in large numbers. 
At a later period, a still more slender, practically thread-like form is 
developed, which is met with chiefly in the proboscis, though also, 
apparently, in the intestine. This type, which differs rather from 
the last, appears to die off if it remains in the leech, and taking 
this in conjunction with the occurrence of these individuals in the 
proboscis, the inference is that this is the form in Avhich the 
parasites are inoculated into the fish. At the close of digestion, 
a number of very small forms are always to be seen, either in a 
rounded (probably resting) condition or in a very early Crithidial 
phase. These seem to be persistent forms, through which the 
leech retains the infection. 

Miss Robertson discusses the likelihood of the two contrasting 
trypaniform types above described representing male and female 
individuals, but for several reasons hesitates to accept this view. 
However this may be, it is more probable that conjugation itself 
takes place soon after the transfer of the parasites from one host to 
the other, i.e. after the arrival in the Invertebrate ; and that the 
ookinete form is the immediate result of the process. This is 
suggested by Lager's work on T. barbatulae, as well as by Keysse- 
litz's account of the life-cycle of Trypanoplasma borreli (27). It 
is also regarded by Prowazek (68) as being the case in T. leivisi, in 
the louse. 

According to Keysselitz, male and female gametes can be 
readily recognised in the blood of the fish (carp), the conjugation 


taking place in the leech, after various regulatory or matura- 
tion processes have been undergone. The copulae give rise to 
the three general types, distinguished principally by nuclear 

In the case of T. lemsi, Prowazek states that soon after reaching 
the mid-gut of the louse, the parasites undergo reduction of the 
nuclear apparatus, by which the number of chromosomes is said 
to be reduced from sixteen to four. The gametocytes (parent- 
individuals of the gametes) are not strikingly differentiated from 
one another, but in the formation of the microgamete from the 
male form, the body becomes diminished in size, its nucleus 
(trophonucleus) very elongated and at first spirally twisted, then 
band-like, while also the cytoplasm stains differently from that of 
the female element (megagamete). 

Coming now to what is known of the development of Mam- 
malian Trypanosomes in Tsetse -flies (Glossinae), we have first to 
mention the knowledge obtained by Minchin, Gray, and Tulloch (59) 
with regard to T. gambiense in G. palpalis. This, unfortunately, ia 
largely of a negative character, owing in all probability (as we have 
seen earlier) to this species of fly not being the correct alternate 
host, but one in which the attempts of the parasite to continue its 
life-history are, for some reason, unsuccessful. Nevertheless, the 
important observation that the types already recognised as male 
and female in the blood of the Vertebrate at first greatly pre- 
dominate, with, moreover, a much more marked differentiation 
of sexual characters and without any forms intermediate in 
type, is also strongly in favour of the idea that conjugation 
occurs, in general, soon after the arrival of the Trypanosomes in 
the insect. 

No mention is made by Stuhlmann (80), in his highly interest- 
ing account of T. brudi in G. fusca, of the occurrence of any similar 
phases, or of anything in the nature of ookinetes, at the beginning 
of the infection. The first individuals found by this investigator 
were of the indifferent type, occurring in large numbers in the 
hinder part of the gut, two to four days after infection of the fly. 
It seems probable, however, that Stuhlmann missed some early 
essential phases of the development, since, as said above, Le"ger 
found ookinetes of T. barbatulae eighteen hours after feeding, while 
Minchin and his collaborators say that the sexual forms were best 
developed after about twenty-four hours, while by the end of forty- 
eight hours a type of more indifferent character was making its 
appearance. According to Stuhlmann, the indifferent parasites 
apparently spread forwards through the mid-gut, but usually pass 
right forward only when the flies are fed again (from an uninfected 
animal). By this means the presence of the Trypanosomes in the 
proventriculus was obtained, and in the "long" form, quite similar 


to the type occurring in the proventriculus and oesophagus of freshly 
caught " wild " flies. 

This type manifestly corresponds to Miss Robertson's very 
slender forms in the front part of the gut and proboscis of the 
leech ; the agreement extends to the ladder-like arrangement of the 
chromatin (chromosomes ?) of the trophonucleus. Whereas, how- 
ever, in T. raiae, it is these forms, or their derivatives, which appear 
destined to return to the fish, Stuhlmann found, in the proboscis 
of freshly caught Tsetses, little Crithidial forms ("small" forms), 
with the kinetonucleus alongside, or on the flagellar side of the 
trophonucleus. 1 Stuhlmann regards these individuals, which he was 
unable to obtain in artificially infected flies, as representing the 
phase in which T. brutii is transmitted to the Vertebrate ; though 
lie states that the long forms seem to degenerate in the pro- 
ventriculus after a time (as well as the small ones). In no case, 
unfortunately, was he able to actually infect a Vertebrate by means 
of either kind, which suggests that there is some other, as yet 
unknown, factor or condition concerned in this perplexing question. 

Stuhlmann describes and figures certain phases found in one case 
in the proventriculus of an artificially infected fly, which he thinks 
are perhaps indicative of conjugation. In all the stages figured, 
the cytoplasmic body of the parasite is single ; the nuclear and 
locomotor organellae, on the other hand, show different conditions 
from single to double. Of course, here as in so many other cases, 
it is entirely a matter of the sequence in which the figures should 
be taken. Stuhlmann's chief reason for his interpretation is that, 
in what he regards as the earlier stages of union, the flagella lie on 
opposite sides of the body ; whereas, in the usual mode of division, 
the two flagella lie on the same side of the body. Still, Stuhlmann 
himself agrees that the condition may be only one of an unusual 
mode of division ; and this seems the more likely explanation, for 
such a mode of division has been observed in T. lewisi. 2 

That the course of a Trypanosome life-cycle may take, however, a 
quite different direction from that outlined in the above instances is 
proved unmistakably by Minchin's valuable investigations on Trypano- 
soma graiji (57 and 58), which led him to the unexpected discovery 
of the encystment of this form in the proctodaeum of G. palpalis. 

Minchin recognises three well-marked types of this Trypanosome 
in the fly. (a) The ordinary type, having a multiplicative function, 
and probably giving rise to the swarm of parasites often found. It 
is usually of large size, and shows great variability, especially in 
the position of the kinetonucleus. While generally a little in front 
(i.e. on the flagellar side) of the trophonucleus, it may be alongside, 

1 For an account of the proboscis - forms recently described by Roubaud, see 
Postscript, p. 261. 2 Cf. footnote, p. 225. 



or even behind it (i.e. nearly terminal at the afiagellar end), though 
it is not often in the last position. Minchin thinks this last form 
most nearly represents that in which T. grayi occurs in its Vertebrate 
(probably Avian) host. The second type (b} is constituted by 
slender, often greatly elongated individuals, with well-developed 
undulating membrane and flagellum. Minchin was at first inclined 
to regard these as male forms ; but from their occurrence in one 
case in remarkable numbers in the proctodaeum, to the exclusion 
almost entirely of any other kind, he has since thought this view 
to be unlikely. The primary habitat of the slender type is the 
proctodaeum, from which region it may extend forward through 
the intestine and stomach of the fly. (c) Small, very narrow forms, 
of a typical Herpetomonas-Yike structure, practically lacking any 

undulating membrane (Fig. 
22, a), which stain more 
faintly and appear much 
more delicate than parasites 
of type (b); the kinetonucleus 
is often relatively large. 
These individuals were found 
in the proctodaeum, and, 
rarely, in the hinder intes- 
tine ; they are apparently 
derived from young forms of 
the indifferent type, pro- 
duced by rapid multiplication 
in the hinder part of the 

It is this Herpetomonad 
type which undergoes en- 
cystment. In cyst-formation 
the flagellum becomes 
shortened and at the same 

time apparently thickened. The cyst begins to appear as a layer 
of substance, probably of a slimy or mucoid nature (cf. Prowazek's 
" Schleimcysten " in the case of Herpetomonas muscae-domesticae 
[69]), which forms a cap at the aflagellar end (Fig. 22, b). These 
two processes continue until, on the one hand, the flagellum is 
completely retracted, and, on the other hand, the body is enveloped 
in a pear-shaped cyst (c), which is at first incomplete at the pointed 
end. The flagellum appears next to become retracted into a pink- 
staining vacuole (cf. the opposite process in the formation of the 
flagellar phase of Leishmania (Piroplasma) donovani) ; finally, the 
flagellar vacuole fades away, the cyst meanwhile closing up. 
Eventually there results an oval or circular cyst, containing hyaline 
cytoplasm and the two chief nuclear masses (d). In this guise, 

FIG. 22. 

Encystrnerit of the narrow, Herpetomonad form 
of Trypanosoma grayi. (After Minchin.) 


presumably, T. grayi passes into the outer world, to be swallowed 
subsequently by its alternate host. 1 

Comparing T. grayi with T. Irucii, an essential point of contrast 
is at once noticed. In the first-named, the small, Herpetomonad 
forms, which have the function of propagating the infection to a 
fresh host, occur mainly in the proctodaeum and leave the fly per 
<ui urn. In the latter, on the contrary, the small, Crithidial forms, 
which are compared by Minchin with those of T. grayi just men- 
tioned, were found almost exclusively in the proboscis ; moreover, 
no Trypanosomes of any kind Avere seen in the hindermost part of 
the gut (proctodaeum). Hence the propagation of T. Irucii would 
appear to be just as certainly by the inoculative method as that of 
T. f/rayi is by the contaminative one. Further, just as there is at 
present no evidence of contaminative infection in T. brucii, so there 
is none of inoculative infection in T. grayi ; for although Minchin 
says that the slender type, which he also thinks is a propagative 
form, was met with farther forward than the Herpetomonad type, 
it was not met with farther forward than the stomach. And this 
is as far as our knowledge goes up to the present. 

Schaudinn's Work on Haematozoa of the Little Owl. 

There remains for consideration the remarkable research of the 
late Fritz Schaudinn on certain parasites of Athene nodua and Culex 
pipiens, namely, I'rypanomorpha (Trypanosoma) noctuae and " Try- 
panosoma " (Lemocytozoon, Spirochaeta) ziemanni. Exigencies of space 
preclude a detailed account of this work, only the main outlines 
of which can be given here, but a full description will be found in 
the writer's article on the Haemoflagellates (3). 

Taking first Trypanomorplw, noctuae, the life -cycle may be con- 
veniently commenced with the motile copula or ookinete resulting 
from conjugation in the stomach of the gnat. While the nuclear 
fusion of the two sets of elements (kinetic and trophic) derived 
from the original gametes is being completed, leading to a single, 
large, compound nucleus, the ookinete is getting rid of unnecessary 
material, such as the pigment-grains and reduction-nuclei left over 
in the cytoplasm (Fig. 10, A, B). Even in the ookinete stage, 
Schaudinn recognises the three types of individual, indifferent, 
male, and female, distinguishable by differences in the size of 
the nuclei relative to the cytoplasm, and by the varying appear- 
ance of the latter. 

The development of an indifferent Trypanosome has been de- 
scribed above (p. 213). When formed, a period of active movement 
and multiplication sets in, succeeded later by a resting condition. The 

1 The reasons for considering that this parasite is not merely a " fly-parasite " 
have been given on p. 201. 


parasites now become gregariniform, and strongly recall the similar 
phase described by Le"ger (48, 51) in certain Herpetomonads. The 
Trypanosome bores into an epithelial cell of the stomach by means 
of its flagellum, which is reduced to a short, rod- like organella. 
Binary fission may go on, often leading to the formation of a dense 
layer of attached parasites. On the parasites again becoming try- 
paniform, the flagellar apparatus is reconstituted by the kineto- 
nucleus. This alternation of resting and active periods is limited. 
Eventually the indifferent Trypanosomes may pass into the blood 




FIG. 23. 

Development of microgametocyte and male Trypanosomes from an ookinete of male character, 
(After Schaudinn.) m.n, male nuclei; f.n, degenerating female nucleus; m.t, male tropho- 
nucleus ; m.k, male kinetomicleus ; M.T, male Trypanosome ; r.b, residual body. 

of the owl ; or they may apparently become sexual forms, male 
or female ; or else, during a period of hunger, they die off. 

In the development of an ookinete of male character, or micro- 
gametocyte, there is an early separation of the nuclear constituents 
into two halves, male and female. The female portion consists of 
a large, loose nucleus (Fig. 23, C and D, f.n), which gradually 
degenerates and disappears. The male portion, on the other hand, 
gives rise to eight little double-nuclei (c and D, m.n), each consisting 
of trophic and kinetic portions. The microgametocyte now becomes 
rounded, the eight double-nuclei take up a peripheral position (E), and 
the cytoplasm opposite each grows out as a little prominence. As- 


these elongate, each accompanied by a double-nucleus, they take on 
a trypaniform appearance, which is completed by the development 
of a flagellum. Finally, the eight little male Trypanosomes (F, .v.r), 
which are homologous with microgametes, break away from the 
central residuum. These forms are apparently incapable of further 
development in any way and soon die off. Schaudinn accounts for 
this by the condition of the trophonucleus, which, he says, has 
undergone reduction. 

The early stages in the formation of a female Trypanosome are 
similar to those in the case of a microgametocyte. Here, however, 
it is the eight small double- 
nuclei, representing the 
male constituents, which 
degenerate, leaving the 
large female nucleus to 
become differentiated and 
give rise to the locomotor 
apparatus in the same way 
as in an indifferent form 
(Fig. 24, c). In the 
females the flagellum, etc., 
is poorly developed, and 
the movements of the para- 
sites are slow and feeble. 
These Trypanosomes seem 
unable to divide. They 
grow to a large size, and 
store up a considerable 
amount of reserve -nutri- 
ment in the cytoplasm. 
These forms are the most 
resistant to external in- 
fluences, and can survive 

long hunger-periods, in a gregariniform, resting condition. 1 With 
the advent of fresh blood into the stomach of the gnat, the female 
forms undergo a process of parthenogenesis, consisting of nuclear 
reduction and a kind of self-fertilisation. Thus rejuvenated, they 
are able to give rise to a fresh succession of Trypanosomes of all 
three types. 

The Behaviour and Development of the Trypanosomes in the Blood of 
tJie Owl. All the Trypanosomes met with in the bird can be recog- 
nised as belonging to one of the three categories observed in the 
gnat. On entering the blood, the small indifferent forms at once 

1 According to Schaudinn, these gregariniform females can bring about hereditary 
infection, remaining dormant in the ovaries until the eggs are laid and the larvae 

Development of a female Trypanosome from an 
ookinete of female character. (After Schaudinn.) 
m.n, degenerating male nuclei ; a.sp, tirst axial spindle 
of female nucleus; f.t, female trophonucleus; /./,-, 
female kinetonucleus. 



attach themselves to the red blood -corpuscles (Fig. 25, A and B), 
and begin a period of rest and growth. The locomotor apparatus 
disappears and the two nuclei come close together. The form of 
the parasite is now quite that of a young Halteridium, a well-known 
malarial parasite of birds, and, moreover, in twenty-four hours the 
first pigment-grains appear in the cytoplasm (c). By this time the 
parasite has greatly increased in size. It becomes vermiform and 
active, reconstitutes its flagellum, etc., and leaves the host-cell (D), 
usually in the night-time, becoming once more a typical Trypano- 
morpha (E). This alternation of attachment and growtli with active 
movement in the plasma is repeated for six days, until the full size 
of the parasite is attained (F and G). The adult Trypanosome then 
undergoes successive longitudinal divisions, until the resulting 
daughter -individuals have reached a minimum size, when they 
repeat the whole cycle. It is worth noting that Schaudirm never 


FIG. 25. 

Stages in the growth of an indifferent Trypanosome in the blood of the owl. n, nucleus 
of red blood-corpuscle ; p, young ectocorpuscular parasite. (After Schaudinn.) 

observed any multiplication of the parasites in the gregariniform 
(Halteridium) condition, by schizogony, such as is met with in other 

Microgametocytes (male forms) arise from very young indifferent 
Trypanosomes. Each gives rise to eight small, slender micro- 
gametes, in the same way as do the corresponding forms in the 
gnat. The microgametes are very specialised organisms. The 
trophonucleus (in a reduced condition) forms a long thread, on 
which four chromosomes are strung at intervals. There is no free 
flagellum at the anterior end, but the body has a whip -like tail 

The full-grown megagametocytes are large female Trypano- 
somes, which are no longer able to assume the trypaniform con- 
dition, but remain enclosed by the pallid and disorganised host-cell 
which they were last able to penetrate. In other words, they are 
identical with the female gametocytes of Halteridium. Maturation 



and fertilisation do not take place until the sexual forms are trans- 
ferred to the gnat. The process in its main outlines has been 
previously described by MacCallum in another species of Halteridium. 1 
Schaudinn adds that, as soon as the parasites leave the warm- 
blooded host, the megagametocytes become rounded off, rupture the 
delicate envelope still surrounding them, and then undergo a series 
of reduction-divisions, after which they are ready to be fertilised. 
The zygote develops into one of the three kinds of ookinete with 
Avhich this description began. 

Leucocytozoon (" Trypanosoma ") ziemanni. Even more surprising 
are the data put forward by Schaudinn in the case of the other para- 
site (or set of parasites) upon which he worked. Just as a species 
of Halteridium is regarded as ontogenetically related to Trypanomorpha 
noctuae, so Leucocytozoon ziemanni, a parasite of the white corpuscles 
and erythroblasts, is said to be intimately connected with what has 
been hitherto taken for a species of the genus Spirochaeta, a well- 
known bacterial type. Far from being, however, a true member of 
the Bacteria, this species at any rate was regarded by Schaudinn 
as possessing all the fundamental 
characteristics of a Trypanosome 
(see Fig. 7, H). 

The plan of the life-cycle is 
fundamentally similar to that 
just summarised, the same sets 
of forms being described. Two 
or three distinguishing features 
may be noticed. The indifferent 
Trypanosomes are extremely 
spirochaetiform (Fig. 26, A-D) ; 
after longitudinal fission, the 
two daughter-individuals remain 
attached end-to-end (B and c), 
the resemblance to a Spirochaete 
being thereby accentuated. 2 The 
resting-phases, little pear-shaped 
forms with two nuclear elements 

(E and F), are Very PiwplaSma- zieimnni;'E, F, resting - phases of "same; O", 
_' . * ,, , agglomerated cluster of very minute forms. 

like and strongly recall the (After Schaudinn.) 
Leishman-Donovan bodies. On 

the other hand, the gametocytes (in the blood of the owl) are 
very large and broad, and distinctly trypaniform, even possessing 

1 See the account of the Sporozoa, by Minchin, in this treatise (Vol. I. Part II. ). 

3 According to Novy, M'Neal and Torrey (64), Ttipfer has recently cultivated a, 
true Spirochaete (i.e. a Bacterium) from the owl, which possesses also minute resting- 
forms. Hence Schaudhm's spirochaetiform " Trypanosoma " may have been really 
this same Spirochaeta. 


FIG. 20. 

; formation and fission of spirochaeti- 
couples " in " Trypanosoma " (Spirochaeta) 


well-marked myonemes. Prior to gamete-formation, both gametocytes 
come into relation with the leucocytes, in an unusual manner (see 
under " Habitat," p. 205), and lose all trace of locomotor organellae. 

Microgamete - formation, maturation 
and fertilisation of the megagamete 
(Fig. 27), in the gnat, present nothing 
unusual. Instead of an ookinete 
giving rise to a single Trypanosome, 
as in Trypanomorpha, it grows con- 
siderably, forming a large coil, and 
nuclear multiplication goes On actively 
at the same time (Fig. 28). Ulti- 
mately, an enormous number of little 
spirochaetiform parasites are pro- 
duced, which populate the alimentary 

tVip crnnl- 
l6 nat> 

^f *V>^ , r.v.l^'k'l^ ^,V 

of this remarkable work 

FIG. 27. 

Fertilisation of a megagamete by a 
microgamete. The trophic and kinetic 
female pronuclei are seen on the left. 

Near the middle lie the two reduction- 

nuclei. The remains of the host -ceil j s based mainly upon the realisation 

together with the cast-off envelope of . f i 

(After that, in SUcll a Complicated Study, 
,, /. ,-, 

there was a grave source of possible 
error, and there is nothing to show that this was eliminated. 
The opinion has been very generally expressed that Schaudinn 
did not sufficiently guard against the liability of confusing and 
mixing up the life -histories of entirely distinct parasites. In 

the parasite are on the right. 


FIG. 28. 

Growth and metamorphosis of an indifferent ookinete ; in C nuclear multiplication is well 
advanced. (After Schaudinn.) 

the first place, it is said that in the species of owl used at least 
four separate Haematozoa occurred : two free parasites, namely, 
a Trypanosome and a Spirochaete (" Trypanosoma " ziemanni) 
and two intracellular ones, a Halteridium and a Leucocytozoon. It 
may be at once admitted that this is quite possible. At any rate, 
the entire subject is reopened and cannot be settled definitely until 


the life-cycle of some or of all the parasites concerned has been 
reinvestigated. (See Note below.) 

While preserving an open mind upon the matter, the writer 
would point out that, if no indubitable confirmation of Schaudinn's 
far-reaching conclusions can be said to have been furnished, the 
merely negative evidence adduced by Novy and his colleagues is 
by no means sufficient proof of their erroneousness. Because the 
injection of cultures of certain Trypanosomes in artificial media, into 
birds, was not followed by the appearance of Cytozoa in the blood, 
these workers apparently conclude (I.e.) that there is no connection 
whatever between these two groups of Haematozoa. And this com- 
prehensive generalisation is put forward, although in nearly all cases 
they failed to obtain even a Trypanosome-infection by this means, 
apart altogether from the question whether the particular form with 
which they did once succeed had itself an intracellular phase ! 

We will admit that the cultivation-method, which is of undoubted 
use in other ways, may not be without value in studying the life- 
history. In certain cases, for example, the behaviour of the parasites 
on their arrival in the culture-medium may to some extent indicate 
or suggest what happens when they pass into the Invertebrate 
host, because of the general similarity of the physical conditions, 
etc., to which they are at first subjected. An illustration of this 
is afforded by the development of the Flagellate phases of the 
Leishman-Donovan bodies in cultures. Nevertheless, we certainly 
think that the value (in this respect) of the cultural method of re- 
search is limited, and that great caution is necessary in drawing infer- 
ences as to a parasite's life-history from the results obtained by it. 
We dissent entirely from the American authors when they maintain 
that the culture-medium is, for all practical purposes, the equivalent 

Note. The present \vriter has always been reluctant to think 
Schaudinn made such a series of mistakes. It has always seemed to him 
that this author's celebrated work on the Coccidia of Lithobius has not 
been taken into account sufficiently by those who have maintained that 
he was hopelessly wrong in the case of the parasites of the Little Owl. 

It is with the greatest pleasure, therefore, that on the point of 
publication of this article, the writer is able to add that after a most 
arduous investigation on the Haematozoa of the common chaffinch 
(Fringillu coelebs), he has at length obtained the first definite and 
iinmistakable evidence, of which he is aware, in favour of one of 
Schaudinn's conclusions. Here, there is only room to .ay that, as a 
result of his observations, he has now little doubt that a Halteridium 
parasitic in the chaffinch becomes actually, in certain phases, a little 
Trypanosome ; in other words, that the Halteridium and the Try- 
panosome which occur in this bird are ontogenetically connected (vide 
Q.J. Micr. Sci. liii. p. 339, Feb. 1909). Hence the writer feels reassured 
with regard to the truth of the corresponding part of Schaudinn'a work. 


of the medium in the Insectan host ; on the contrary, we consider 
that the former, whatever indications it may furnish, cannot replace 
altogether the latter. 

It seems to us that Novy and M'Neal entirely fail to appreciate 
the intimate and specific relations of Protozoan parasites to their 
hosts, and the remarkable degree to which their biology is adapted 
to the same. The Sporozoa in their entirety illustrate this, so do 
other parasitic Protozoa, and there is no reason to suppose the Haemo- 
flagellates are different. We agree fully with Brumpt that the 
chemical and physiological medium of a particular Invertebrate is 
essential for the adequate development of all such phases of the 
life-history of a Trypanosome as may be undergone outside the 
Vertebrate host. And the various researches above summarised, 
which go to show that there are right and wrong hosts for the 
parasites, and that only certain " ripe " phases, the outcome of the 
sojourn in the right host, can reinfect the Vertebrate host success- 
fully, afford strong support to this view. 

Another criticism put forward by Novy and M'Neal and others 
is that the Flagellate phases found in the mosquitoes (Culex), Avhich 
Schaudinn regarded as belonging to Trypanomorpha of the Little 
Owl, were in all likelihood purely Insectan parasites, of a Herpeto- 
monad or Crithidial type, which had nothing to do with the blood 
forms. Before discussing this view it is necessary to consider 
briefly the subject of these Insectan Flagellates, one which is also of 
very great importance because of its bearing upon the phylogeny 
and derivation of the Trypanosomes. 


(a) The Insectan Flagellates. 

Several of the earlier workers have commented upon the occur- 
rence of Flagellates in mosquitoes. Thus in 1898 Ross observed 
parasites which he has recently (74) compared with Leger's genus 
Crithidia in Anopheles, larva, pupa, and imago. A similar parasite 
was found by Christophers in 1901, occurring in swarms in 
Anopheles and Culex. Durham, again, the } r ear before, had 
noticed numerous " Trypanosomes " in a Stegomyia which had fed 
upon a bat. The first serious contributions, however, to our know- 
ledge of the Flagellates parasitic in Insects are Leger's researches 
(47, 48, 51, 52), 1902-1904, on certain Herpetomonadine forms. 

Besides the genus Herpetomonas, Le"ger has distinguished 
another type of form, which he has termed Crithidia. Both types 
show, in general, an alternation of monadine (flagellate) phases 
with gregariniform (resting, non- flagellate) ones. In the latter 
condition, the parasites occur as small, rounded, pear-shaped, or 



even oblong bodies, attached, often in great numbers, to the 
epithelial cells. The flagellum is either absent or reduced to a 
short rostrum, serving for attachment (Fig. 29, D and G). The 
t\vo nuclei (tropho- and kinetonueleus) lie close together, usually 
near the base of the cell. In this phase, the general resemblance 
to the Leishman-Donovan bodies may be quite marked. The 
distinction between the two generic types is based upon the form 
and size of the monadine phase. In Herpetomonas the body is very 
elongated . and slender, often acicular, the posterior end usually 

FIG. 29. 

A, C, Herpetomonas (Crithidia) minuta ; D, attached (gregariniform) phases of same; B, H. 
gracilis, Leger ; E. F, //. subulata, Leger ; G, attached phases of same. (After Leger.) x 1800. 

tapering away finely (Fig. 29, B and E). In Crilhidia, on the other 
hand, it is much shorter and wider, of a pyriform shape ; the hinder 
end is never drawn out, but terminates bluntly in a rounded or an 
obtuse manner. The parasite Herpetomonas (Crithidia) minuta, L6ger, 
appears to be intermediate, however, between these two types, some 
individuals approximating to a Herpetomonad form (A), others to a 
Crithidial one (Fig. 29, c). As a matter of fact, the classificatory 
distinctions between these various Insectan Flagellates cannot be 
regarded as at all settled. 

In many forms of Herpetomonas (e.g. H. muscae-domesticae, 1 H. 
jaculum, or H. gracilis (B)), the kinetonucleus is situated near the 

1 //. muscae-domesticae is included here as a typical uiiiflagellate Herpetomonad. 
Prowazek (69) described this form as possessing a pair of flagella, parallel to and 
connected with one another ; he considered this parasite to be a bipolar type (on the 
lines of Schaudhm's " Urhaemoflagellate") in which the body has been bent up so 
that the two ends have come together and united, the flagella alone remaining 
distinct. Leger observed no signs of two flagella in non-dividing individuals, either 
of this species or others ; and the same is true of the describers of the numerous 
other Herpetomonads. 



anterior end ; the flagellum is not attached to the side of the body at 
all but straightway becomes free, and there is no sign of an undulat- 
ing membrane. These forms are mostly parasitic in Invertebrates 
which do not suck blood. In H. subulata, however, which is parasitic 
in the digestive-tube of Tabanus and Haematopota, predatory on cattle 
and horses, the kinetonucleus lies much farther from the anterior 
end, and may be almost opposite the trophonucleus (Fig. 29, F). 
The flagellum, which has been, as it were, drawn back with it, is in 
most individuals attached for the proximal part of its length to the 
anterior part of the booty, by means of a delicate cytoplasmic 
border, which constitutes a rudimentary undulating membrane. 
Thus there is an approach to a trypaniform condition. Again, in 
the case of Crithidia fasciculata, found in the intestine of mosquitoes, 
Leger has described a very distinct undulating membrane, which 
gives the parasite, especially in the more elongated individuals, a 
very Trypanosome-like appearance. Novy and his colleagues have 
also studied C. fasciculata, as found in Culex but while admitting 
the presence of a membrane, regard it as imperfect and only 
poorly developed. These authors describe, in addition, another 
Herpetomonadine type, H. (Trypanosoma) culicis, the long forms of 
which show clearly an undulating membrane. 

We are now in a position to discuss the relation (if any) of 
these Flagellates to the Trypanosomes of Vertebrates. When 
first describing Crithidia, Leger expressed the opinion that this 
parasite was very likely only a stage in the development of a 
Haemoflagellate ; further, in his notes on H. subulata (52) he 
added the remark that the same was probably true of many of these 
Herpetomonad or Crithidial forms found in biting Insects, though 
this would not apply, of course, to those species occurring in non- 
biting Insects (such as Musca, Sarcophaga, etc.). Moreover, Schaudinn 
himself (I.e.) comments on the great similarity between (what he 
took to be) the phases of Trypanomorpha noctuae in Culex and those of 
Le"ger's Crithidia. 

Quite the opposite view is held by Novy and M'Neal, who, 
after first (62) regarding the Flagellates found by Schaudinn in 
mosquitoes as being simply "cultural" forms, of no real significance 
in the life-history, in their later paper (63) consider it much more 
likely that the Insectan parasites are entirely distinct from the 
Trypanosomes in the blood. (They look upon the parasites found 
in leeches, however, as "cultural" forms of Piscine Trypanosomes.) 
A similar opinion is expressed by Ross, who points out that he 
found Crithidia in the mosquitoes (larvae and pupae) before they 
fed on blood, and thinks the parasites were in the first place 
swallowed by the larvae. 

In a very interesting note Patton has recently (65) described 


stages in a Herpetomonas of Culex pipiens, whose life-cycle would 
seem in some respects to conform to the scheme suggested by Ross. 
In its monadine, determinative form, the parasite appears to be a 
typical Herpetomonas, with no indications of an undulating membrane. 
All the phases observed, Patton states, exhibit great similarity with 
those of Piroplasma donovani (see pp. 256 et seq.). Here it may be 
pointed out that in the larvae the parasites resembled the Leishman- 
Donovan bodies as they occur in human tissues ; in the nymphs, 
stages corresponding to the developmental forms of the Leishman- 
Douovan bodies (in cultures, or in the bed-bug), i.e. pear-shaped forms 
with flagella, were numerous ; while in adult mosquitoes (mid- and 
hind-gut) there were fully developed Herpetomonad forms. Patton 
thinks these are passed out into the water, and in some guise or other 
ingested by the larvae, the cycle thus beginning again. (He has 
privately informed the writer that the parasites may encyst in the 
rectum, and be thus passed out to the exterior, to give rise to the 
small round forms in the larva.) Patton also notes the occurrence 
of a Herpetomonad, which has an obvious undulating membrane, 
and which possesses similar rounded aflagellar forms, in a water- 
bug. The author concludes by regarding these two parasites as 
limited to their Insectan hosts. 

In endeavouring to draw some general conclusions from the 
above opposing ideas, we are, it seems to the writer, greatly helped 
by comparing what is known in the case of other groups of Trypano- 
somes. In the first place, as regards those met with in Tsetse-flies, 
some of which, at any rate, were formerly considered to be solely 
fly-parasites, there appears to be no escape from the conclusion that, 
on the contrary, all the forms are blood-parasites. In our opinion 
the utmost weight is to be attached to this conclusion. In addition, 
we have the Trypanosomes of leeches, which are generally agreed to 
belong to different Piscine forms. On these grounds alone, then, it 
appears justifiable to suppose that Avian -Trypanosomes are to be 
found in mosquitoes, and not at all improbable that some at least 
of the phases so clearly described by Schaudinn from mosquitoes 
which had fed on infected owls, did indeed appertain to Trypano- 
morpha noduae. 

Again, to consider the subject from the Insectan standpoint, so 
far as the writer can see, Novy and his colleagues have by no 
means proved that their Flagellates in wild mosquitoes are not, in 
some cases at any rate, phases of Trypanosomes of birds (or other 
Vertebrates). For instance, the Trypaiwsoma (Herpetomonas) culicis 
described by these authors with various forms of which they 
compare certain phases of Trypanomorplia is quite as probably a 
blood-parasite as a purely Insectan form ; indeed, the possibility of 
this being so is admitted by its describers. Moreover, they remark 
on the resemblance between the genera Herpetomonas, Crithidia, and 


Trypanosoma, especially when the "cultural" forms of the last-named 
are compared with those of the other two (or with what Novy and 
M'Neal regard as their equivalents the Insectan forms). In the 
case of the Trypanosomes, there is the same relative position of the 
two nuclei, either close together, or the kinetonucleus even on the 
flagellar side of the trophonucleus ; while certain of them show no 
sign of an undulating membrane, but have a typically Herpetomonad 
facies. Novy and M'Neal, in fact, would include all these types in 
the genus Trypanosoma. 

Further, we may point out that according to the view which 
these authors themselves hold regarding the origin of the blood- 
Try pan osomes, it is most natural to suppose that they are to be 
met with, quite at home, in an Insectan host. The American 
workers say that parasitism in the living blood is to be looked upon 
as the result of previous adaptation to the more or less digested 
blood (in the Invertebrate). (As will be seen later, we agree with 
this view, where certain Insects are the Invertebrate hosts.) Now, 
in this course of evolution of certain blood-Trypanosomes, it may 
be reasonably inferred that at one stage the parasites still remain 
connected with the Invertebrate after having gained a footing in the 
Vertebrate (say a bird). The question would seem to be, rather, 
which if any blood-forms so descended have lost the ability to live 
(and develop) in their Invertebrate host a course which would 
probably greatly restrict their opportunities for dispersal. (In this 
connection the case of the Leishman-Donovan bodies is most 
instructive ; cf. pp. 258, 259.) 

Hence, summing up, there can be little doubt that certain of 
these parasites of mosquitoes, especially those with trypaniform 
characters, are connected with some Vertebrate host, just as are 
those of other blood-sucking Invertebrates. At the same time, it is 
also probable that some of the (typical) Herpetomonads found (e.g. 
those occurring in larvae, such as Patton's form, also certain forms, 
described by the Sergents) are simply and primarily parasites of 
the Insect. Lastly, it is, of course, possible that such a parasite 
may have developed a trypaniform condition as an adaptation to 
the food of a sanguivorous Insect, without, however, having become 
able to live in the Vertebrate host ; but so far no example of such 
a case is definitely known. And this brings us to the subject of 
the derivation of the Trypanosomes. 

(b) Evolution and Phytogeny. 

It must be fully recognised that any views which can be at 
present advanced upon this interesting, but very puzzling topic are 
at best little more than speculations. Formerly (I.e.), the writer 
inclined to the idea that all Haemoflagellates are to be derived from 


forms originally parasitic in Invertebrates ; in other words, the 
Invertebrate was regarded as the primary host, the Vertebrate as 
the secondary or intermediate one. We now think this view was 
probably, to a considerable extent, wrong ; in this we have been 
mainly influenced, on the one hand, by the intestinal Trypanoplas- 
mata, and on the other, by the case of T. grayi. As above remarked, 
it seems evident that a Vertebrate is the primary host of this latter 
parasite ; and the same would follow, by inference, for the other 
(Mammalian) Trypanosomes transmitted by Tsetse-flies. Moreover, 
the writer thinks he did not allow sufficient weight to the fact 
that the Invertebrates which harbour Trypanosomes are, with but 
few exceptions, blood-suckers. For these reasons we are now inclined 
to consider most of the Invertebrates concerned (e.g. leeches, many 
biting-flies, etc.) as the secondary, intermediate hosts of various 
Vertebrate parasites (probably all the Piscine and Amphibian ones, 
many, but perhaps not all the Mammalian ones, and perhaps some 
Avian ones). 

The only important 1 exceptions are among Insects ; and here 
it is quite likely that we have both primary and secondary hosts. 
Besides the Tsetses, Tabanids, etc., the common house-fly and 
related genera, in which Herpetomonads (e.g. H. muscae-domesticae, 
H. sarcophagae, etc.) occur, ought apparently also to be placed in 
the category of secondary hosts. For Prowazek (I.e.) states 
that, according to Brauer, the latter flies are probably de- 
scended from blood-sucking ones; in Avhich case their parasites 
may very well be descended from haemal forms, which are now, 
perforce, restricted to the Invertebrate host. On the other hand, 
there are several instances of the parasites occurring either in non- 
sanguivorous Insects or in forms that only rarely suck blood, 
which are, we think, more likely cases of primary parasitism. 
Among these, for example, are H. bombycis, in Bombyx mori ; H. 
gracilis, in larvae of Tanypus ; Crithidia campanulata, in larvae of 
CMronomus plumosus. Lastly, we have the mosquitoes and their 
parasites, both of imago and larva. The latter is, of course, 
aquatic, and the imago is by no means limited to blood for nutri- 
ment. Having regard also to the illustrative series of transitional 
forms between the monadine type and the trypaniform one, made 
known by Leger and others, it appears to us that here as well the 
Insect is the primary host of the various Flagellates concerned, and 
that where these are connected with a Vertebrate host the latter is 
to be regarded as the secondary, intermediate one. This would 
apply chiefly to certain parasites (e.g. Trypanomorpha) of birds, 
though not necessarily, it is to be noted, to all. 

Many authorities (such as Laveran and Mesnil, Liihe, Novy and 

1 Herpetomonas biitschlii from a Nematode (Trilobus) and the curious Trypano- 
phis from Siphonophores do not appear to have any bearing upon this question. 


M'Neal) have maintained the view that the Invertebrate is the 
primary host in all cases. Minchin, however, has always considered 
the Vertebrate as the principal host ; and in his latest memoir 
on the Trypanosomes of Tsetse-flies (58), proofs of which he very 
kindly allowed the writer to see, he regards all Trypanosomes as 
descended from an intestinal Vertebrate form, and indicates the 
lines upon which the evolution may be supposed to have advanced. 
This ancestral form produced resistant cysts for dispersal, and thus 
contaminative infection was brought about. (It would be extremely 
interesting to ascertain whether the intestinal Trypanoplasmata 
known (see p. 249) have such a cyst-formation.) The next stage in 
evolution is when the parasite has penetrated the intestinal wall, 
and come into relation with the circulatory system. Until it came 
into relation with a blood-sucking Insect, this type would have to 
pass back into the alimentary canal for dissemination. So far, we 
have no evidence of an existing instance of this stage. Subsequently, 
the blood-parasite became adapted to an Insectan host, in the gut 
of which it encysted, reinfection of the Vertebrate being by the 
contaminative method. T. grayi in all probability furnishes an 
example of this type. Lastly, the parasite is thoroughly adapted 
to the biology of the Insect and passes forwards to the front part 
of the alimentary canal : infection of the Vertebrate is now by the 
inoculative method. This may possibly be combined in some cases 
with the contaminative mode, but probably in most encystment no 
longer takes place, being unnecessary (e.g. the lethal Trypanosomes, 
Piscine forms, etc.). 

Of course, in those cases where, as above remarked, the Verte- 
brate is probably the secondary host, there is no reason to suppose 
that, as a rule, the parasites leave the circulatory system. 

Phylogeny. As stated at the beginning of this article, the 
Trypanosomes, as a whole, are to be regarded as including two 
entirely distinct families, in one of which (the Monadine type) the 
attached flagellum becomes free at the true anterior end, and in the 
other (the Heteromastigine type) at the true posterior end. The 
former type is derived by the progressive migration backwards of the 
kinetonucleus towards the posterior (aflagellar) end, in the manner 
well illustrated by Leger's series of Herpetomonadine forms (see 
Fig. 29). The latter type is derivable from a Trypanoplasmatine 
ancestor itself in turn doubtless to be derived from a fiodo-like 
form by the loss of the anterior free flagellum ; l so that the non- 
flagellate extremity is the true anterior one. 

The writer is unable, owing to limits of space, to enter fully 

1 A comparison of the different degree of development of the flagella in various 
forms is instructive as illustrating the manner in which the Trypauoplasmatine condi- 
tion may have resulted from that found in Bodo, and its further evolution. 


here into the reasons for and against this diphyletic view, which 
was first put forward by Le"ger (49). A complete discussion will 
be found in his Review of the Haemoflagellates (pp. 270-278). 
Liihe, in his account of the Haematozoa in Mense's Handbuch der 
Tropenkrankheiten (2), has adopted it, though on somewhat different 
lines from those taken by us. Minchin, also, has expressed the 
opinion (Brit. Mai. Journ., 1907, ii. p. 1320) that - Trypanosomes 
are most likely diphyletic. On the other hand, many authorities, 
including Laveran and Mesnil, hold the view that all Trypanosomes 
are descended from Herpetouionadine ancestors, basing their opinion 
on the resemblance to a Herpetomonad shown by many Trypano- 
somes in cultures, and by young individuals of T. leivisi (cf. Fig. 20). 
In many cases, at any rate, we regard this phase as we have 
previously said rather as a " pseudo-Herpetomonadine " condition ; 
and in such cases do not attribute to it the phylogenetic importance 
which is done by some, but consider it to be probably capable of 
explanation on other grounds (see I.e.}. A fact which seems to us 
of considerable significance is that Trypanoplasmatine forms are 
known to occur in the digestive tract of fishes, e.g. " Trypanoplasma " 
intestinalis in Box boops, and " T." rentriculi in Cydopterus lumpus; 
moreover, another Heteromastigine parasite (Bodo lacerfae) is found 
in a lizard. On the other hand, no indubitable Herpetomonad has 
yet been described from the alimentary canal of a Vertebrate, which 
we may assume to have been the original habitat of the primitively 
Vertebrate parasites. 

Hence, all things considered, we come to the general conclusion 
that the Trypanosomes which have the Vertebrate for their primary 
host are Heteromastigine forms ; those derived from primitively 
Invertebrate parasites, on the other hand, are probably Monadinc 
forms. Endeavouring to use this view practically, for purposes of 
classification, or, at any rate, of convenient partition of the Trypano- 
somes, we have as follows : The parasites of fishes belong to the 
Heteromastigine type ; this can be said with some degree of 
confidence, in spite of the " Crithidial " forms assumed by the 
parasites in leeches. Probably the same is true also of most forms 
of cold-blooded Vertebrates. Of the Avian ones, on the contrary, 
some at any rate (e.g. those of the type of Trypanomorpha noctuae) 
are Herpetomonadine forms. Among Mammalian parasites the 
various lethal Trypanosomes (e.g. T. brucii, etc.) are to be regarded 
as Heteromastigine forms. We will only mention in passing that 
certain movements of these forms in the living blood (cf. p. 217) 
suggest very forcibly that the aflagellar end is the true anterior 
extremity. Of the other known (accustomed) parasites of Mammals, 
whose number has considerably increased of late, it is quite possible 
that some (e.g. those of bats, which may have, perhaps, mosquitoes 
as their alternate hosts) are Herpetomonadine forms. 



The reasons for the division of the Trypanosomes into two 
distinct families have been alluded to in the previous section. 
Besides the fundamental diagnostic characters, namely, the true 
orientation of the body and the biological features associated there- 
with, it is quite likely that important differences in regard to the 
life-cycle will become evident as our knowledge increases. 


Family TRYPANOMORPHIDAE, Woodcock. Haemoflagellates 
derived from a uniflagellate, Herpetomonadine form, in which the 
point of insertion of the flagellum into the body has travelled back- 
wards from the anterior end for a considerable distance, the 
flagellum itself having become, concurrently, attached to the body 
for part of its length by means of an undulating membrane. At 
present only one genus is distinguished. 

Genus Trypanomorpha, Woodcock. With the characters of the 
family. The genus was founded for Schaudinn's Avian parasite, 
Trypanosoma (Halteridium) noduae (Celli and San Felice), 1 from 
Athene noctua and Culex pipiens. As above mentioned, it is probable 
that other Avian forms, and perhaps some Mammalian ones, will be 
found to agree with this generic type ; at present, however, it is 
not possible to say which with any certainty, and hence they are 
retained under the heading " Trypanosoma." 

Reference has been made to the possibility of Leger's Crithidia 
fasciculata from Anopheles maculipennis, and other Insectari parasites 
which show marked trypaniform characters, being also really 
Haemoflagellates. In such a case the genus Trypanomorpha may 
prove to be synonymous with Crithidia ; if so, the latter name will 
take priority. Ltihe, it is to be noted, in his account of the 
Haematozoa (I.e.), regards all the Trypanosomes of Mammalia as 
belonging to the Herpetomonadine type, and has proposed the new 
generic name Trypanozoon for these forms. 


Family TRYPANOSOMATIDAE, Doflein. Flagellates, with but 
few exceptions haemal parasites, derived from a bi flagellate, Bodo- 
like type, in which the posteriorly directed (trailing) flagellum is 
always present and attached to the side of the body by an undu- 
lating membrane, of which it constitutes the thickened border. 

1 Schaudinn placed this form in the genus Trypanosoma. We incline, however, 
to the view that the type-species of that genus (T. rotatorium) is a Heteromastigine 
type, and therefore restrict that genus to such forms. 



The other, the anterior flagellum, may or may not persist. At 
least three genera known so far. 

Genus Trypanoplasma, Laveran and Mesnil. The anterior 
flagellum is present. 

Type-species, T. borreli, Lav. and Mesn. (Fig. 11). Length of body 
20-22 /*, of free flagella 13-15 /x, breadth 3^-4^ p.. Parasitic in Leuciscus 
erythrophthalmus, rudd, and Phoxinus laevis, minnow. Other species are T. 
cyprini, from the carp, and T. varium, a rather larger form, from the loach. 

Genus Trypanophis, Keysselitz. The anterior flagellum is pre- 
sent. The free part of the posterior flagellum is short, and the 
undulating membrane is straight and relatively narrow. The 
species for which this genus was founded is parasitic in certain 
Siphonophores, and almost certainly not a haemal form. 

e.C, - 

Fit;. 30. 

Trypanophis grcitjbeni (Poche). e.c, ectoplasmic cap; e.l, delicate ectoplasmic layer, thin- 
ning out posteriorly ; i, inclusions in the cytoplasm ; x, nuclear body of uncertain origin and 
significance. (After Keysselitz.) 

Type-species, T. yrobbeni (Poche). Average length 60-65 //,, width 
about 4 p.. From Cucubalus kochii, Halistemma teryestinum, Monophyes 
gracilis, Gulf of Trieste. Apparently the same parasite has also been 
observed in Abyla pentagona, Gulf of Naples. The organisms are to be 
found in all the ramifications of the coelenteron, from the digestive-cavity 
of the gastrozoids to the radial canals of the medusoid buds. Nothing 
is known with regard to the transmission from one Siphonophoran colony 
to another. 

Great interest attaches to certain Trypanoplasmatine parasites 
recently described from the alimentary canal of fishes. In their 
general morphology and the possession of an undulating membrane 
they agree closely with Trypanoplasma, and their describers have 
included them in this genus, as T. intestinalis, L6ger, and T. ven- 

2 5 


triculi, Keysselitz. So far as those points are concerned, however, 

they agree also with the above-mentioned genus Trypanophis (cf. 

Figs. 30 and 31). Indeed, Leger, in his account of T. intestinalis, 
commenting on the great resemblance of this 
parasite to Trypanophis, suggested that the latter 
form might be included in Trypanoplasma. We 
consider that Trypanophis grobbeni, on account 
of its curious habitat and somewhat peculiar 
nature, should certainly be kept distinct. More- 
over, as regards the intestinal Trypanoplasma- 
tine forms, the fact that they are most likely 
not haemal parasites renders it very probable 
that their life-cycle differs in many ways from 
that of the ~b\ood-Trypanoplasmata (cf. the hypo- 
thetical stages in evolution outlined above, 
p. 246). Formerly, we placed " T." intestinalis 
with Trypanophis on these grounds ; but it seems 
preferable to consider it as belonging to an 

down the side near the independent genus, along with " T" ventriculL 

undulating-membrane (cf. 

in B the As we are averse to the practice of instituting 

; t i /-irt-1-iV.ift - 1 - " 

FIG. 31. 

" Trypanoplasma " in- 
testinalis. In A a row of 
spherules is seen running 

kinetonucleus is double. . . , 

(After an original draw- new genera in a treatise, we do riot propose to 

Lege^f^ ^ ^ ^ d SO here - 

Before leaving this point, it may be noted 

that, in the case of these Heteromastigine forms, the presence of 
an undulating membrane and consequent trypaniform appearance 
does not bear the same relation to a haemal habitat as seems to 
be the case in the Monadine types. As Doflein has already pointed 
out, 1 the undulating-membrane, in the Trypanoplasmatine parasites, 
has doubtless been developed as the result of the contiguity of the 
trailing flagellum of the Bodonine type to the side of the body ; 
a quite different origin from that in the other section. Hence this 
condition is more or less independent of the habitat of these forms. 
Genus Trypanosoma, Gruby (principal synonyms : 2 Undulina, 
Lank., 1871 ; Herpetomonas, Kent, 1880, but only in part, since 
the type-species is H. muscae-domesticae ; Paramoecioides, Grassi, 
1881; Haematomonas, Mitrophan., 1883; Trypanomonas, Danil., 
1885, for young forms). There is no anterior flagellum. The 
point of insertion of the attached (posterior) flagellum into the 
body, and, consequently, the commencement of the membrane, may 
be anywhere in the anterior half of the body, but is usually near 
the extremity. 3 

1 Die Protozoen als Parasiten und Kranklieitserreger (Fischer, Jena, 1901), 
p. 54. 

2 For remarks on the synonymy of this genus, readers are referred to the writer's 
previous article (p. 287). 

3 The type-species is T. rotatorium, Mayer, of frogs. At present, unfortunately, 
this parasite cannot with certainty be included in the above diagnosis, owing to its 



The sub-classification of this genus, or rather the grouping and 
arrangement of the numerous Trypanosomes at present included in 
it, is a question of great difficulty and one in regard to which 
hardly anything has been done as yet. 1 This is chiefly owing to the 
fact that so little is still known of the life-history of most that 
hitherto any attempt to group the parasites has been dependent upon 
their adult morphology. This is not a very satisfactory criterion, 
since, as we have seen, on the one hand, the differences in this 
respect between different forms may be very slight ; and on the 
other, a particular parasite may itself vary very greatly at different 
times and under different conditions (see under " Morphology "). 
Moreover, it may very well be that as more life-histories come to be 
revealed, some of the forms at present placed for convenience in 

FIG. 32. 

A, Tri/iKuwsoma gamliiense (from the blood), after Bruce and Labarro ; B, T. equinum, after 
Lignieres ; C, T. evansi, from an original drawing ; D, T. cquiperdum, after Lign. 

the genus Trypanosoma will have to be transferred to new ones 
(as an example may be mentioned T. grai/i). 

For the present, at any rate, a very useful aid towards dis- 
tinguishing different species is furnished by the biological relations 
of the parasites. For it may be assumed that here, as is usual 
among the Sporozoa, a particular species is, in general, restricted 
either to one particular host, or, at most, to a few allied ones. 
Difficulty arises in considering the Mammalian forms, many of 
which have never been observed in the true, natural hosts, but only 

unusual shape, position of kinetonucleus, etc. The occurrence, however, of an 
allied form in Hyla, which is evidently intermediate between T. rotatorinm and 
the more typical, fusiform species, suggests that the former also belongs to the Hetero- 
mastigine section. 

1 Koch, however, has attempted a classification of the Mammalian forms, which he 
arranges in two groups, the first including such different forms as T. lewisi and the 
large T. theileri of cattle ; the other, most of the lethal forms, which he considers 
are not distinct species. This arrangement is very artificial and has nothing to 
recommend it. 



in various unaccustomed animals, for which they are more or less 
lethal. The important immunisation experiments first carried out 
by Laveran and Mesnil, and since then by other workers, have 
shown, however, that several of the parasites causing the different 
trypanosomoses now known are distinct species. 

A full description of all the known forms and tlieir characteristics is 
impossible within the limits of this article. It must suffice to mention 
some of the more important and better-known parasites, arranged under 
the different classes of Vetebrate hosts ; for fuller details regarding them, 
reference should be made to the writer's previous account, or to Nabarro's 
revised edition of Laveran and Mesnil's treatise, which is most useful in 




FIG. 33. 
A and B, T. theileri; C-E, T. "transwalien*:." x 1250. (After L. and M.) 

this connection. A list of known hosts and their Trypanosomes is given 
at the end of this chapter. 

(a) Parasitic in Mammals. Trypanosoma lewisi, Kent, the common 
natural parasite of rats (Figs. 7, A ; 20, A). Length * 24-25 p., breadth 
l|-2 p.. This species is characterised by its narrow and pointed aflagellar 
extremity, and by the position of the trophonucleus in the flagellar half 
or third of the body. The cytoplasm is usually free from granules. T. 
Irudi, Plitnmer and Bradford. Length 28-30 p., breadth 2-2| //. The 
anterior end is usually bluntly rounded (Figs. 7, B ; 17, A). The cytoplasm 
often contains granules in the posterior half. Natural hosts probably 
various Antilopidae (e.g. gnu, " koodoo," etc.), and buffaloes. The cause of 
Nagana or Tsetse-fly disease in cattle, horses, etc., in South Africa. T. 
gambiense, Button (Syn. T. ngandense, Castell). Length 21-23 fj., breadth 
1^-2 /JL. This species (Fig. 32, A), according to its average size, is one of 
the smallest known. The cause of human trypanosomosis in West and 

1 The dimensions given are intended to indicate the average size of the parasite in 
each case, but can only be considered as approximate. The length is inclusive of the 
flagellum, unless otherwise stated. 


Central Africa. The earlier stages of the disease, when the parasites are 
confined to the blood, are known as Trypanosoma-k\er ; the later ones, after 
the organisms have penetrated into the cerebro-spinal canal, constitute the 
deadly malady of sleeping-sickness. The true, natural host is unknown. 
T. equinum, Voges (Syn. T. elmassiani, Lign.). Length 22-25 p, width 
1^-2 /j.. Distinguished from all other forms by the minute size of the 
kinetonucleus (Fig. 32, B). Hydrochoerus capybara is almost certainly a 
natural host. Other well-known lethal parasites are : T. evansi (Steel), of 
Surra in horses in Indo-Burmah (Fig. 32, c) ; T. eqiiiperdum, Doflein (Syn. 
T. rouyeti, Lav.), the cause of Dourine in horses, transmitted naturally by 
coitus (Fig. 32, D) ; T. theileri, Laveran, a very large form, often surpassing 
50 p. in length, which causes "bile-sickness" of cattle in the Transvaal 
(T. transvaaliense, Lav., with the kinetonucleus near the middle of the 

FIG. 34. 

T. johnstoni. g, deeply-staining granule at 
distal extremity of flagellar border, x 1500. 
(After Dutton and Todd.) 

Fl - 35. 

A Trypanosome from Sene- 
gambian birds, x 150C. (After 
D. and T.) 

body (Fig. 33, C-E), has been shown to 
be, in all probability, only a phase of 
T. theileri) ; and T. dimorphon, Dutt. 
and Todd, which gives rise to a trypano- 
somosis of horses in Senegambia. 

(6) Parasitic in birds. T. avium, 
Danil., Lav. emend., probably the form 
to which Danilewsky's original investi- 
gations related, occurring in owls and, 
according to Novy and M'Neal, in 
various other birds. Length 35-45 />t 
(Fig. 7, F). T. johnstoni, Dutt. and 

Todd. Length 36-38 //., width 1^- p.. 
TVn -nnrnsitp in <5O lpnrlpr i<5 'iltnnst- 

llns parasite is so i as almost 

to justify the description spirochaeti- 

form (Fig. 34). From Estrelda. The opposite extreme of form is 

seen in a Trypanosome, T. hannae, Pittaluga, originally described by 

Hanna (25) from an Indian pigeon (Fig. 7, o) ; this is relatively 

very broad, and has, moreover, a long, attenuated aflagellar extremity, the 

latter character being not unusual in bird-Trypanosomes. On the other 

FIG. 30. 

T. paddae. At x the base of the flagel- 
lum is thickened prior to division. 
X 1200. (After Thiroux.) 



hand, Button and Todd have described a wide form from Senegambian 
birds, which has this end bluntly rounded, giving the parasite a stumpy 
appearance (Fig. 35). It is interesting to note that this Trypanosome 
occurred in the same birds (Estrelda) in which the very different T.johnstoni 
was found. T. paddae (Fig. 36), from the Java sparrow, has been studied 
by Thiroux (83), and apparently lends itself to cultivation and inoculation 
into other birds as readily as do many Mammalian forms. Finally, there 
is the remarkable parasite, " T." (Spirochaeta) ziemanni, described by 
Schaudinn. If this form is really a Trypanosome, it certainly belongs 
to the Heteromastigine section, and may for the present be placed in the 
genus Trypanosoma. But it may be, after all, a true Spirochaete, and 
belong to the Bacteria (cf. footnote, p. 237). 

(c) Reptilian forms. Scarcely any Trypanosomes have been observed 
in Reptiles. The only one which has been figured is T. damoniae, Lav. 
and Mesn. Length 32 /A, breadth 4 //,. The general structure (Fig. 7, j) 
presents nothing unusual. As in Piscine forms, the body is often rolled 
up on itself. From Damonia reevesii, a tortoise. Another form (T. boueti), 
lately described from a lizard, is said to resemble the flat, smooth type 
of T. rotatorium (below). 

(d) Parasitic in Amphibian hosts. The Trypanosomes of frogs show 
a remarkable variation in form, size, and appearance, and it is not at all 
certain, in some cases, how far this is due to polymorphism, and how far 
to distinct species being concerned. The type-species of the genus is T. 
rotatorium (Mayer). (Synn. Amoeba rotatoria and Paramoecium costatum 
or loricatum, Mayer, July 1843 ; Trypanosoma sanyuinis, Gruby, Nov. 

1843 ; Undulina ranarum, Lank., 
1871.) Laveran and Mesnil have 
worked on this form and dis- 
tinguish two principal types, one 
having the surface of the body 
thrown into parallel ridges (Figs. 
8, B ; 37, A), the other having a 
smooth, regular surface (Figs. 8, A ; 
37, B). The parasites are very 
large, being 40-60 //, in length, by 
from 5-40 p. in width ; the two 
dimensions vary more or less in- 
versely. The great variation in 
shape of the body and of the 
anterior end is seen from the 
figures. The kinetonucleus is 
aisually situated some distance from the non-flagellate or anterior extremity, 
.and may be quite close to the trophonucleus ; sometimes, however, it is 
fairly near the end. Chiefly for this reason, Franca and Athias (22) 
split up the species into two, T. costatum or loricatum (Mayer), with the 
kinetonucleus near the centre, and T. rotatorium, with it near the end. 
As the position of this organella is very variable and intermediate stages 
occur, we do not think anything is gained by doing this, at present. 
-Similarly, the validity of two new species which Franca and Athias 

FIG. 37. 

T. rotatorium (Mayer). Bibbed and smooth 
forms, x 1000 (approx.). (After L. and M.) 



create, namely, T. undulans and T. elegans, is somewhat doubtful. Button 
and Todd have described two very long forms from Gambian frogs, which 
they have named T. mega and T. karyozeukton ; these forms exhibit 
peculiarities in the cytoplasm (see p. 212), and in the latter parasite a 
chain of chromatic granules runs from one nucleus to the other (Fig. 8, D). 
A type which is certainly distinct is T. inopinatum, Sergent, from the 
edible frog. This parasite (Fig. 8, c) is slender (25-30 /z by 3 //,), and 
resembles a Mammalian or Piscine form. Another well-characterised 
species is T. nelspruitense, Lav., in which the body is very vermiform and 
the free flagellum very long (Fig. 8, E). 

(e) Forms parasitic in fishes. Trypanosomes occur very frequently 
in fishes, and a great many species have been described. T. remuki, 
Lav. and Mesn. This para- 
site occupies about the same 
position among Piscine Try- 
panosomes as does T. lewisi 
among Mammalian ones. It 
is a slender form, with taper- 
ing, pointed extremities. The 
trophonucleus is in the pos- 
terior half of the body. Para- 
sitic in Esox lucius, the pike. 
Laveran and Mesnil have dis- 
tinguished two varieties, based 
upon the considerable differences in size met with, namely, var. parra, 
medium length 30 /x, of free flagellum 10-12 /JL, with breadth 1^-2 p. ; and 
var. magna (Fig. 8, L), minimum length 45 /x, of which 17-20 /A is for the 
flagellum, and breadth 2-2J //,. T. cobitis and T. carassii (Mitrophanow) 
were among the first Piscine forms to be described, and probably corre- 
spond to many of those seen by Danilewsky. T. granulosum of the eel 
is a remarkably long, eel-like form (Fig. 8, K), 70-80 //. by 2|-3 p. The 
kinetonucleus is relatively very large, as is often the case in Piscine forms, 
and close to the anterior end, which is sharply acute. Several forms 
have been observed in flat-fish, certain of which (e.g. T. flesi, Lebailly) 
belong to a different type, being relatively wide, with only a short 
flagellum. From Elasmobranchs, two very large forms (T. scyllii and 
T. raiae) have been described by Laveran and Mesnil ; these attain a 
length of 70-80 yit, and usually have the body coiled up on itself (Fig. 

FIG. 38. 

A, T. scyllii ; B, T. raiae. x 1200. 
(After L. and M.) 



Although these remarkable bodies have not been shown yet to 
possess an actual trypaniform structure, the fact that they are known 
to give rise to Flagellate phases of very Herpetomonadine character 
points so conclusively to their connection with that type of parasitic 
Flagellate, and is of such importance as proving that a parasitic Flagellate 


can and does become intracellular in the Vertebrate host, that a brief 
consideration of them is essential to the completeness of this article. 

The Leishman- Donovan bodies are constantly found in certain 
tropical fevers (such as Dum-dum fever, Kala-Azar), particularly pre- 
valent throughout Indo-Burmah, of which they are now generally admitted 
to be the cause. These parasites were discovered by Leishmau in 1900, 
but before his first account of them was published (91) they were also seen 
independently by Donovan. Moreover, organisms very similar to these 
parasites (indeed, morphologically, the two kinds are hardly distinguish- 
able) are found in various sores or ulcers (known as Delhi boil, Oriental 
sore, " bouton d'Alep "), to which people in different parts of the tropics 
are liable. The latter were first clearly recognised and described by 
Wright (97). 

In the former type of disease, there is a general systemic infection, 
the parasites spreading to all parts of the body, and being met with in 
the spleen, where they are usually very abundant, liver, bone-marrow, 
and (more rarely) in the peripheral circulation. The latter type of 
disease, on the other hand, is one of localised infection, the organisms 
being restricted to the neighbourhood of the skin lesions ; and in this 
case the parasites never seem to become distributed throughout the body, 
producing a systemic infection. For this reason, though the organisms 
in the two cases seem to be undoubtedly closely related, they are probably 
specifically distinct. In the Vertebrate host, the parasites are generally 
intracellular. Free forms are met with, doubtless liberated by the break-up 
of the host-cells, but these probably soon invade fresh cells. Leish man's 
form is parasitic in large uninuclear leucocytes (Fig. 39, II), and especially 
in cells of the vascular endothelium, which are often packed with the 
little bodies, becoming greatly distended (as macrophages). According to 
both Donovan (88) and Laveran and Mesnil (90), the parasites also 
occur in the red blood-corpuscles. Wright's form occurs in the ulcer 
cells, and in large migratory corpuscles (phagocytes) of the granulation- 

The parasites themselves are very minute, and usually ovoid or 
pyriform in shape, the latter being perhaps the more typical. The 
splenic form is somewhat smaller than the localised type, being 3|-4 p, 
in length by l|-2 p. in width (39, I), while Wright's form is about 4 fj. 
by 3 //, (39, III). The cytoplasm is finely granular and fairly uniform 
in character ; but sometimes it is vacuolated. The most interesting 
point about the morphology is the fact that two chromatic bodies, of very 
unequal size, are invariably to be recognised. The larger nuclear body, 
which corresponds to the trophonucleus of an ordinary Haemoflagellate, 
is usually round or oval ; the smaller one, representing a kinetonucleus, 
has the form either of a little rod or of a round grain, and stains very 
deeply. The two nuclei are generally quite separate, but sometimes they 
appear to be connected. The organisms multiply in two ways : (a) by 
binary fission, and (6) by multiple division or segmentation. The chief 
stages in the first method are well known (Fig. 39, I, 6) ; they offer great 
resemblance to the corresponding process in Piroplasma. Multiple division 
has not yet been so satisfactorily made out. It appears to conform more 



or less to the radial or rosette type of multiplication (I, c), enlarged 
rounded parasites, with a varying number of nuclei (up to about 10) 
uniformly arranged near the periphery, having been often noticed. The 
details are, however, rather differently described by different workers. 

Our knowledge of any further development undergone by these 
parasites is limited at present to the Leishman-Donovan bodies, and is 
due in the first instance to Rogers (94). Rogers cultivated the parasites 



F/o. 39. 

I, Leishmania (Piroplasmu) donovani (Lav. and Mesn.). a, typical pear-shaped or oval forms ; 
6, various stages in binary fission ; c, nuclear division, preparatory to multiple fission ; d, Rndo- 
corpuscular forms in red blood-corpuscles (p, pigment grains) ; e, bacillary form of the parasite 
in a corpuscle ; M, large macrophageal cell with many parasites. (After Donovan.) II, Uni- 
nuclear leucocyte (L) containing several parasites. (After L. and M.) Ill, L. (P., Helcosama) 
troj>i<-<i (Wright), a, single individuals ; b, dividing forms. (From Mesnil, mostly after Wright.) 
IV, L. (P.)donocani in cultures of different ages, a, ordinary forms of varying size ; 6, c, stages 
in multiple division ; e, /, and g, flagellate forms. (After Rogers.) 

in citrated blood, at a lower temperature, and made the astonishing 
discovery that Flagellate forms were developed from them. This result 
has since been fully corroborated and further details ascertained by Christo- 
phers (87), Leishman and Statham (92), and others. Different stages 
in the process are seen in Fig. 39, IV, d-g ; and Fig. 40. The parasites 
increase greatly in size and become vacuolated (this is probably due to 
the artificial medium in which they are). Multiplication by binary fission 
takes place, and with successive generations the shape of the body alters ; 
from being pyriform it passes through a fusiform condition, and finally 
becomes elongated and slender. Meanwhile, in many of these phases, a 


2 5 8 


flagellum has made its appearance ; when this is fully developed the 
parasite quite resembles an ordinary Herpetomonas. 

The origin of the flagellum is interesting. A distinctive vacuole-like 
structure arises near the end which will become the flagellar end, in close 
connection with the kinetonucleus a point, probably, of importance. 
This vacuole increases and suddenly is ruptured, some of its contents 
being extruded to the exterior as a tuft or fringe of pink -staining 
substance. In the middle of this, a small flagellum is seen, but how 
exactly it is formed is not known. Once constituted, the flagellum grows 
rapidly. Even in the most fully-developed Flagellate phases, however, 
in no case has anything comparable to an undulating-membrane been 
observed. The kinetonucleus is comparatively near one end of the body, 


FIG. 40. 

Stages in the development of the flagellated form. (From Leishman.) 1, ordinary spleen 
parasite ; 2, 3, growth and vaeuolisation in cultivation ; 4, 5, appearance and growth of the 
special " flagellar vacuole," close to the kinetonucleus ; 6, rupture of this vacuole and protrusion 
of a tuft of pink-staining threads ; 7, growth of the flagellum, its base being inserted in the 
collapsed vacuole ; 8, acquirement of the Herpetomonad form. 

and the flagellum springs directly from that end, not being actually 
connected, apparently, with the former organella. 

Another remarkable process observed in these developmental forms in 
cultures is unequal longitudinal fission. Very thin, sickle-like (" spirillar ") 
portions of the body are split off from one side of a parent-individual. 
More than one of these thread-like forms may be successively cut off. The 
unusual feature of the process is that neither the two principal nuclear 
elements nor the flagellum take part in it. Subsequently, these fission 
forms seem to give rise to very slender flagellar ones. To what extent 
this represents a normal (natural) mode of multiplication is uncertain. 

No other stages have been observed in cultures, and the organisms 
degenerate and ultimately die off. The above facts demonstrated, how- 
ever, that the Leishman-Donovan bodies can undergo important changes 
outside the human host, and rendered it probable that they do so 
naturally, though whether in the free condition or in an alternate host 
was, until lately, quite unknown. The superficial position of the localised 
form (Wright's type) points very strongly to infection by means of some 
biting Insect, and it is natural to infer that the same holds also for the 


splenic type, when its occurrence in the circulation is borne in mind. 
Here, again, Kogers gave the lead. This worker, finding that the parasites 
developed flagellar stages most readily in an acid medium, suggested (95) 
that the stomach of some blood-sucking Insect (such as a flea or bug) was 
probably the place where the above described extra-corporeal phases of 
the parasite's existence would be found to occur. This has been recently 
proved to be the case by Patton (93), who has found the Flagellate phases 
in the bed-bug (Oimex rotundatus [macrocephalus]). It is most probable, 
therefore, that the infection of human beings is brought about by this 
Insect, which serves as an alternate host. 

The systematic position and affinities of this parasite have been much 
discussed. Leishman at first considered the organisms as representing 
involution-forms of Trypanosomes, being largely influenced by the two 
chromatin masses ; in this view he was supported by Marchand and 
Ledingham. Later, he went farther and suggested that they perhaps 
represented an actual stage in a Trypanosome life -cycle. Laveran and 
Mesnil, taking more into account the general form and very suggestive 
binary fission, thought a new species of Piroplasma was concerned, and 
named the bodies Piroplasma donovani ; in this view Donovan and others 
have concurred. Other authorities (e.g. Christophers, Ross, and Wright) 
thought they saw in the parasite an entirely different kind of Sporozoan. 
Ross called the splenic type Leishmania, and a little later, Wright termed 
the ulcer- form Helcosoma tropicum. Recently, Rogers has placed the 
Leishman-Donovan form in the genus Herpetomonas, on account of the 
similarity in the Flagellate- phase. 

It is probably best to regard the parasites as generically new forms ; 
in this case the splenic form becomes Leishmania donovani and the ulcer- 
type, which is most likely a separate species, L. tropica. The organisms 
are closely related, on the one hand, with the Herpetomouads, and on 
the other with the Piroplasmata. With regard to the parasites possessing, 
at some period or other, a trypaniform structure, the complete absence of 
an undulating-membrane in the cultural forms is no proof that one is not 
present under certain conditions in Nature. For, as already noted, many 
Trypanosomes, when " cultivated," may have a very slight indication of 
a membrane or none at all. Nevertheless, it is by no means improbable 
that these parasites have remained solely Herpetomonad forms and have 
not developed the characteristics of a Trypanosome. The fact that the 
Flagellate-phase is only known to occur in the Invertebrate host, points 
very strongly to this being the original primary host. In this connection 
the Herpetomonas lately described by Patton from Culex pipiens (to which 
reference has been made above) is very interesting, because of the occur- 
rence of resting- phases resembling the Leishman bodies. Leishmania 
may well be a similar form which, parasitic in a sanguivorous Insect, 
has become adapted to the Vertebrate host in its resting, gregariniform 
phase, and perhaps never develops a trypaniform condition, or even an 
active flagellar phase therein. Turning to the other side, there can be 
little doubt that the Piroplasmata are intimately connected with the 
Leishman-Donovan- Wright bodies. The general agreement of the intra- 
cellular forms as regards appearance and binary fission has been noted 


above. In addition, there is the most important point that some species 
of Piroplasma are stated to show, at certain times, the same characteristic 
nuclear dimorphism. Schaudinn was the first to notice this, in the case of 
P. canis ; and he was confirmed by Kossel and Weber. Since then additional 
observations to the same effect are recorded by other workers (e.g. Liihe) 
for various species. This being so, the Piroplasmata also are most 
probably to be derived from Flagellate forms. 1 

(B) A word or two, lastly, with reference to the supposed connection 
of the Spirochaetae with the Trypanosornes. Besides the instance of 
Trypanosoma (Spirochaeta) ziemanni, Schaudinn, in his great memoir (I.e.), 
was inclined to consider that other Spirochaetae (e.g. S. obermeieri of 
relapsing fever) were also only phases in the lii'e-cycle of other Haemo- 
flagellates. Subsequently, however, as a consequence of his investigations 
on Spirochaeta plicatilis, the type-species, and other forms, he relinquished 
this view, finding that the latter were of a totally different nature, and 
should rather be placed with the Bacteria. Much has since been written 
with regard to the nature and affinities of the various Spirochaetae. We 
do not propose to go into the general question here, as the preponderance 
of opinion is decidedly against these organisms belonging to the Protozoa. 
It is only necessary to mention one or two forms which have been 
definitely referred to the Trypanosomes. Certes, in 1882, described a 
parasite from the digestive tube, including the crystalline style, of oysters, 
which he named Trypanosoma balbianii. A few years ago Laveran and 
Mesnil (99) re-examined this organism, and came to the conclusion that 
it was not a Trypanosome but a Bacterium, allied to Spirochaeta. Other 
workers who have recently observed this form also agree that its structure 
shows none of the essential features of a Trypanosome, but, on the contrary^ 
greatly resembles that of a true Spirochaete. Perrin, it may be noted, 
has endeavoured (100) to connect it with Schaudinn's bipolar " Ur- 
haemoflagellate." This idea has received no support, and indeed Perrin's 
whole paper is most unconvincing. Another, much more important 
example is that of the remarkable spirochaetiform parasite first described 
by Schaudinn and Hoffmann (103) in cases of syphilis, and which is 
now considered to be most likely the cause of that disease. Schaudinn 
found (102) that this organism differs in many ways from an ordinary 
Spirochaeta, and placed it in a new genus Treponema as T. pallidum. 
In a recent memoir (101), Krzysztalowicz and Siedlecki have given a 
detailed account of this organism, and state that they have observed 
distinct trypaniform stages in its life-cycle. For this reason they con- 
sider it to be allied to the Trypanosomes and place it actually in the 
genus Trypanosoma, as T. luia. This view lacks, as yet, corroboration, 
and so here, as in the case of Schaudinn's research, the question must 

1 Since this was written we are able to add that confirmation of this view is forth- 
coming. In a most important note, Miyajima (Philipp. J. Sci. ser. B, ii. 1907, p. 
83) describes the development of Flagellate-phases in cultures of a Piroplasma 
(cf. parvum) of cattle in Japan. In seventy-two hours, forms with well-developed 
undulating-membrane were numerous. The author seems to have carefully guarded 
against the possibility of this highly-interesting occurrence being due to undetected 
Trypanosomes present in the blood. 


be left unsettled. There is one point, however, which may not be 
without significance, namely, the considerable resemblance between the 
biology of this parasite in relation to its host (i.e. as regards mode of 
infection, habitat, connection with the lesions, etc.) and that of Trypano- 
soma equiperdum, the cause of Dourine or " horse-syphilis " (cf. above, 
pp. 197, 206). 


As this article goes to press, a most interesting note by Roubaud 
(G.B. Ac. Sci., 24th Feb. 1908, p. 423) comes to hand. This worker 
has been investigating the relation between certain lethal Trypanosomes 
(T. fjambiense, T. brucii, T. dimorphon, and others) and Glossina palpalis, 
and finds that the parasites undergo important changes as soon as they 
arrive in the proboscis of the Tsetse-fly. The kinetonucleus passes to the 
middle of the body, the undulating-membrane disappears, the flagellum 
becomes short and thickened, and the parasites quickly attach themselves 
to the wall of the proboscis by the flagellar end. The whole process may 
be accomplished, indeed, in five minutes. Moreover, active multiplica- 
tion goes on, and after a time an immense number of attached Trypano- 
somes are present throughout the entire proboscis, often grouped in 
masses or colonies. This " temporary culture " (culture d'attente) 
persists for two days in the case of T. brucii, and longer up to five to six 
days in the other forms. 

This remarkable development is apparently specific for Glossinae ; 
it only occurs in a small number, and is doubtless due to the influence of 
special properties of the salivary fluid. As Roubaud remarks, it prob- 
ably affords an explanation of the selective role played by the Tsetses in 
the propagation of different trypanosomoses in Africa. Roubaud, how- 
ever, considers that these forms found in the proboscis are the only ones 
capable of giving rise to an infection in a Vertebrate after the lapse of 
twenty-four hours. This is going too far, in view of the facts now known 
with regard to the length of time Trypanosomes may live and develop 
in the digestive tract of Glossinae (cf. pp. 200, 230). It is noteworthy that 
Roubaud was unable to obtain a successful inoculation from a proboscis 
so infected. Moreover, the repeated failures of investigators to infect 
animals from flies after forty-eight hours (cf. pp. 199, 200) seem to show 
that the later-developed " proboscis-forms " at all events are not infective, 
since they may reasonably be supposed to have been present in some of 
the many experiments tried. On the other hand, there is an important 
observation made by Bruce when working on T. brucii, to which Mincliin 
(58, p. 210) has drawn attention, showing that "wild" flies, caught 
while feeding on a healthy animal, could infect another animal on which 
they were subsequently fed. This certainly points to the presence of 
some developmental phases in the Insect other than Roubaud's proboscis- 
forms ; the proboscis had been presumably "cleaned" by the first bite 
on the uninfected animal on which the fly was caught. And this view is 
entirely borne out by Stuhlmann's recent research, summarised in the body 
of this article. 




[In the compilation of this list, Nabarro's edition of Laveran and Mesnil's 
Treatise has been of considerable service to the writer. ] 


? Bovidae (Indian, indigenous) . 
? B. (various, African) 


Catoblepas gnu, gnu, "wildebeeste 
? Cattle ("hill," India) 

Cavia cobaya, guinea-pig 

Cricetus frumenlarius (arvalis), 


Hydrochoerus capybara, capybara 
Lepus cuniculus, rabbit 
Meles taxus, badger . 
Miniopterus schreibersii, bat 
Mus decumanus, se\ver-rat . 

M. rattus, black rat, M. rufescens 
M. sylvaticus, field rat 
M. musculus, mouse . 

M. niveiventer, rat (Indian) 
Myotis murinv-s, a bat 

Myoxus avellanarius, M. glis, dormice 

Nesokia (Mus) gigantcus, bandicoot 
Phyllostoma sp. See under Stegomyia 
Pipistrellus pipistrellus, bat 

Pteropus medius, a bat 

Sciurus palmarum, squirrel (Indian) . 
Spermophilus guttatus, S. musivtis, 


Strepsiceros capensis, "koodoo" 
Talpa europaea, mole 
Tragelaphus scriptus sylvaticus, ' ' bush - 

buck " 

Trypanosoma evansi (Steel). 

T. theileri, Lav., and T. transvaaliense, 

Lav. [most probably = T. theileri]. 
T. brucii, Bradford and Plimmer. 
T. brucii. 
T. himalayanum, Lingard (syn. T. 

lingardi, Blanchard) [perhaps = 

T. theileri]. 
A Trypanosome [possibly a Trypano- 

plasma], Kunstler, 1883. 
T. rabinowitschi, Brumpt (syn. Try- 

panozoon criceti, Liihe). 
T. equinum, Voges. 
T. cuniculi, Blanchard. 
T. pestanai, Bettencourt and Franga. 
A Trypanosome [Dionisi, 1899]. 
T. lewisi (Kent) ; T. longocaudense, 

Lingard [probably = T. lewisi}. 
T. lewisi (Kent). 
T. sp. [lewisi 1], Gros, 1845. 
T. duttoni, Thiroux ; T. musculi [syn. 

T. d. ?], Kendall. 
T. longocaudense, Lingard [probably 

= T. lewisi]. 
T. nicolleorum, Sergent, E. and E. 

[perhaps syn. T. vespertilionis, 

T. blanchardi, Brumpt (syn. T. myoxi, 

T. bandicotti, Lingard. 

T. sp. (compared with T. nicolleorum), 

A Trypanosome [Donovan, in Lav. and 

Mesn., 1904]. 

T. (Trypanozoon) indicum, Liihe. 
A Trypanosome [Chalachnikov, 1888]. 

T. brucii, Br. and PI. 
T. talpae, Nabarro. 
T. brucii. 



Vespertilio kuhli, bat . 

V. noctula, bat ..... 
Vesperugo nattereri, V. pipistrellus 
("pipistrelle"), V. serotinus, bats 

T. nicolleorum, Sergeut, E. and E. ; 

T. vespertilionis, Serg. [both perhaps 

synn. T. vespertilionis, Battaglia], 
T. vespertilionis, Battaglia. 
T. dionisii, Bettencourt and Fran9a 

[perhaps syn. T. vespertilionis, 


Various Trypanosomes which have been given distinct names have been lately described 
from certain Equiclae and Bovidae in different regions of Africa, as the cause of more or less 
pronounced trypanosomosis. It is probable that some of these, at any rate, are really forms 
of other better-known African parasites. They are mentioned here, in order to complete an 
enumeration of species, for purposes of reference. They are T. cazalboui, Lav. ; T. congdense, 
Broden ; T. nanurn, Lav. (an extremely small form); T. pecaudi, Lav. ; T. soudanense, Lav. ; 
7'. mi ix, Ochmann ; and T. vivax, Ziemann. The true (natural) hosts are uncertain. 


Agelaius phoeniceus, red-winged black- 

Alcyon sp., kingfisher (Cameroon) 

Asturinula monogrammica, hawk 
(Congo State) 

Athene noctua, little owl 

A. brama, owl (Madras) 

Buteo lineatus, red-shouldered hawk . 
Bycanistes buccinator, trumpeter hnrn- 


Chelidon urbica, house-martin 
Colaptus auratus, " flicker " 
Columba sp., pigeon (Indian) 
Coracias garrulu, roller-bird 
Corvus sp., crow or raven (Indian) 


Crithagra sp., "millet-eater" 
Cyanocitta cristata, blue jay 

Dryobates villosus, hairy woodpecker . 

Emberiza citrinella, yellow-hammer . 
Estrelda estrelda, "millet-eater" 
Fringilla (Carduelis) carduelis, gold- 
F, coelebs, chaffinch . 


T. atrium (type L. and M.), [Novy and 

M'Neal, 1905]. 

A Trypanosome [Ziemann, 1905]. 
A Trypanosome [Button, Todd and 

Tobey, 1907]. 
Trypanomorpha ( Trypanosoma) noc- 

tuae (Schaud.) ; also Trypa/nosoma 

[Spirocliacta ?] ziemanni (Lav.). 
A Trypanosome [Donovan, in Lav. and 

Mesn., 1904]. 

T. mesnili, Novy and M'Neal. 
A Trypanosome [Button, Todd and 

Tobey, 1906]. 

A Trypanosome [Petrie, 1905]. 
T. aviurn (type Lav. and Mesn.). 
T. hannae, Pittaluga. 
T. "avium," Banilewsky. 
A Trypanosome [Hanna, 1903]. 
A Trypanosome ? [Gros, 1845]. 
T. sp. [Button and Todd, 1903]. 
T. avium (type L. and M.) ; also T. 

sp. [Novy and M'Neal, 1905]. 
T. sp. incert. [Novy and M'Neal, 

T. sp., perhaps avium [Cerqueira, 


A Trypanosome [Petrie, 1905]. 
T. johnstoni, Button and Todd. 
T. sp. [Sergent, E. and E. , 1904]. 

A Trypanosome [Ziemann, 1898 ; also 

Petrie, 1905]. 
A Trypanosome ? [Gros, 1845]. 



ffarporhynchus rufus, brown thrasher 
Hirundo rustica, swallow . 

Icterus galbula, Baltimore oriole . 
Laniarius cruentus, shrike (African) . 
Linota (Acanthis) rufescens, redpoll 
Melospiza fasciata, song-sparrow . 
Merula migratoria, robin (American) . 
M. merula, blackbird .... 
Milvus govinda, kite (Indian) 

Neophron percnopterus, vulture (African ) 
Nicticorax gardenia (Brazil) 

Padda oryzivora, Java sparrow . 
Passer domesticus, sparrow . - . 
Passerine birds, many (except Corvus 

and Pica) 
Polyplectrum germani, pheasant 


Scolephagus carolinus, rusty blackbird 
Sialia sialis, bluebird 
Spinus tristis, goldfinch (American) 
Sylvia atricapilla, black-cap warbler . 
Syrnium aluco, tawny owl . 

2'achyphormus ornata .... 
Treron calva, dove (Angola) 
Turdus musicus, song-thrush 
Troglodytes aedon, house-wren 
Zenaidura macroura, mourning-dove . 

A Trypanosome [Novy and M'Neal, 

T. mathisi, Serg., E. and E. ; a Try- 
panosome (T. m. ?) fPetrie, 1905]. 

T. avium (type L. and M. ). 

A Trypanosome [Neave, 1906]. 

T. sp. [original observation]. 

T. avium (type L. and M.). 

T. avium (type L. and M.). 

A Trypanosome [Petrie, 1905]. 

A Trypanosome [Donovan, in Thiroux, 

A Trypanosome [Neave, 1906]. 

T. sp., perhaps avium [Aragao, in Cer- 
queira, 1906]. 

T. paddac, Thiroux. 

T. avium (type L. and M.). 

Trypanosomes [Sjb'bring, in N. and 
M'Neal, 1905]. 

T. polyplectri, Vassal. 

T. sp., Novy and M'Neal. 
T. avium (type L. and M. ). 
T. laverani, Novy and M'Neal. 
T. sp. [Sergent, E. and E., 1904]. 
T. avium, Danil., emend. Lav. ; also 
"T." [Leucocytozoon] ziemanni (Lav.). 
A Trypanosome [Cerqueira, 1906]. 
A Trypanosome [Wellmau, 1905]. 
A Trypanosome [Petrie, 1905]. 
A Trypanosome [N. and M'N., 1905]. 
T. avium (type L. and M.). 


Crocodile (Uganda; .... 
Crocodilus cataphractus ? (Congo) 

Damonia reevesii, tortoise . 


Mabuia raddonii, a lizard (French 

Python . . . 

Snake (unspec., Gambia) 

Tortoise (Indian Emys or Kachuga 

Tortoise (unspec., Gambia) 

A Trypanosome [Minchin, Gray and 

Tulloch, 1906]. 
A Trypanosome [Dutt., Todd and Tob., 


T. damoniae, Lav. and Mesn. 
A Trypanosome [Gehrke, 1903]. 
T. boueti, Martin. 

" T." pythonis, Robertson [really a 

A Trypanosome [Dutton and Todd, 

A Trypauosome [Simond, in L. and M., 

A Trypanosome [Dutton and Todd, 





Bufo vulgaris and viridis, toads . 
B. rcticulatus (Somaliland) . 
Diemyctulus viridescens (American 

Frogs (unspec., Gambia) 

Hyla arborca and H. viridis, tree-frogs 

//. latcristriga (?), Brazil 
Rana angolcnsis (Transvaal) 
H. esculcnta, edible frog 

7i. temporaria 

7v'. t. (?) (Hong Kong) . 
.K. theileri (Transvaal) 
It. trinodis (?) and other sp. (Gambia) 

T. rotatorium (Mayer). 
T. somalcnse, Brumpt. 
A Trypanosome [Tobey, 1906]. 

T. mega and T. karyozeukton, Duttoii 
and Todd. 

T. rotatorium (Mayer); T. sp. [?], 
Lav. and Mesn. 

T. borreli, Marchoux and Salimbeni. 

T. nelspruitense, Lav. 

T. rotatorium (Mayer). (Syn. T. 
loricatum or costatum (Mayer) and 
T. rotatorium (Mayer), Fran9a and 
Athias ; T. r. var. nana, Sergent, E. 
and E. ; T. inopinalum, Sergent, 
E. and E. ; T. elegans and T. undu- 
lans, F. and A. [doubtful species].) 

T. rotatorium (Mayer). 

T. belli, Nabarro. 

T. nelspruitense, Lav. 

T. rotatorium (Mayer). 

(Tpl. Trypanoplasma.) 

Abramis brama, bream 

Acerina cernua, pope .... 

A nguilla vulgar is, eel ... 
Bageus bayard, bagara (Nile) 
Barbus camaticus (India) . 

B. fluviatilis, barbel .... 

Blennius pholis, blenny 

Bothus rhombus (Rhombus laevis), brill 

Box boops ...... 

Callionymus dracunculus . 
Carassius auratus, goldfish 

C. vulgaris, Prussian carp . 

Clarias (Silurus) clarias, a Silurid 

C. angolensis (Congo State) 

Cobitis barbatula, loach 

T. abramis, Lav. and Mesn. ; Tpl. 

abramidis, Brumpt. 
T. accrinae, Brumpt ; & Trypanoplasm 

[Keysselitz, 1906]. 
T. granulosum, Lav. and Mesn. 
A Trypanosome [Neave, 1906]. 
A Trypanosome [Lingard, 1904]. 
T. barbi, Brumpt ; Tpl. barbi, 


T. delagei, Brumpt and Lebailly. 
T. bothi, Lebailly. 
Tpl. [?] intestinalis, Leger. 
T. callionymi, Brumpt and Lebailly. 
T. danilewskiji, Lav. and Mesn. 
T. carassii (Mitropban.). (Syn. Haema- 

tomonas c., Mitis ; T. piscium and T. 
fusiforme piscium, Danilewsky. ) 
T. clariac, Montel. 

A Trypauosome [Button, Todd and 

Tobey, 1906]. 
T. barbatulae, L^ger ; Tpl. varium, 




C. fossilis . 

Coitus bubalis 

C. gobio, river bull-head 

Cycloptcrus lumpus, lump-fish 
Cyprinus carpio, carp .... 

Esox lucius, pike .... 

Gobio fluviatilis, gudgeon . 
G. giuris (India) .... 
Gobius niger, goby .... 
Leuciscus (Scardinius), erythroph- 

thalmus, rudd or red-eye 
L. idus, L. cephalus, L. rutilus, roaches 

L. spp 

Limanda platessoides .... 
Lota vulgaris ..... 

Macrodon malabaricus (Brazil) . 
Macrones seenghala, M.tengara,Si\nri(.\s 

M. cavasius (India) .... 

Mugil sp., noke (Nile) 

OphiocepJialus striatus, Silurid (India) 

Perca fluviatilis, perch 

Phoxinus lacvis, minnow 

Platoplirys laternae . 

Pleuronectcs flesus (Flesus vulgaris), 

P. platessa (Platessa vulgaris), plaice . 

Polypterus sp., dabib (Nile) 

Raia clavata, E. macrorhynchus, B. 

mosaica, and E. punctata, rays 
E. microccllata ..... 
Ehamdia queler (Brazil) 
Saccobratichus fossilis, a Silurid . 
Salmo fario, trout . 

Scyllium canicula, S. stellare, dogfish 

T. cobitis (Mitroph. ). (Syn. Haemato- 

monas c., Mitr. ; T. piscium and 

T. fusiformc, Daiiilewsky. ) 
T. cotti, Brumpt and Lebailly. 
T. langeroni, Brumpt ; Tpl. guernei, 


Tpl. [?] ventricuU, Keysselitz. 
T. danilewskiji, Lav. and Mesn. ; Tpl. 

cyprini, Plehn. 
T. remaki, Lav. and Mesn. ; Tpl. sp. 

[Minchin, 1908]. 
T. elegans, Brumpt. 
T. sp. [Castellani and Willey, 1905]. 
T. gobii, Brumpt and Lebailly. 
Tpl. Worrell, Lav. and Mesn. ; T. 

scardinii, Brumpt. 
A Trypanosome and Trypanoplasm 

[Keysselitz, 1906]. [Probably Tpl. 

borreli and T. leucisci.] 
T. leucisci, Brumpt. 
T. limandae, Brumpt and Lebailly. 
A Trypanosome and Trypanoplasm 

[Keysselitz, 1906]. . 
T. macrodonis, Botello. 
A Trypanosome [Lingard, 1899]. 

A Trypanosome [Castellaui and 

Willey, 1905]. 

A Trypanosome [Neave, 1906]. 
A Trypanosome [Lingard, 1899]. 
T. percae, Bmmpt ; also a Trypauo- 

plasm [Keysselitz, 1906]. 
T. danilewskyi (?), Lav. and Mesn.; T. 

phoxini, Brumpt ; Tpl. borreli, Lav. 

and Mesn. 

T. laternae, Lebailly. 
T. flesi, Lebailly (syn. T. pleuro- 

nectidium, Robertson). 
T. platessae, Lebailly (syn. T. pleuro- 

nectidium, Roberston). 
A Trypanosome [Neave, 1906]. 
T. raiae, Lav. and Mesn. 

A Trypanosome [Robertson, 1906]. 

T. rhamdiae, Botello. 

T. saccobranchi, Castellani and Willey. 

Tpl. truttae, Brumpt. [Valentin, in 
1841, observed a Haematozoan, 
which was probably either a 
Trypanosome or a Trypanoplasm.] 

T. scyllii, Lav. and Mesn. 



tiilurus giants .... 
Solea vulgaris, sole 
Squalius (Leuciscus) cephalits, chub 
Synodontis schal, gargur (Xile) . 
T!i''i tinea, tench 

Trichognster fasciatus (India) 

A Trypanosome [Keysselitz, 1906]. 

T. soleae, Lav. and Mesu. 

T. squalii, Brumpt. 

A Trypanosome [Neave, 1906]. 

T. tincae, Lav. and Mesn. ; a Trypano- 

plasm [Keysselitz, 1906], 
A Trypanosome [Lingard, 1899]. 


Anopheles maculipennis 

A. m. (larvae) .... 

Anopheles sip., mosquitoes (India) 

Bombyx mori, silkworm 
Chironomus plumosus 
Cimex rotundatus, bed-hug (India) 
Culexfatigans .... 

C. pipiens ..... 

Dasyphora pratorum . 
Glossina fusca .... 
G. morsitans and G. pallidipes . 
G. jtalpalis .... 

G. tachinoides .... 
Haematopinus spinulosus, rat-louse 
Haematopota italica 
Hippobosca rufipes, (?) //. maculata 
Homalomyia scalaris . 
Mclophagus ovinus, sheep-louse . 

Musca domestica ..... 
Nepa cinerea ..... 
Pollenia rudis ..... 
Pulex sp., fleas ..... 

Sarcophaga haemorrhoidalis, blow-fly 
Stcgomyia fasciata .... 
S. f. (an individual which had fed on 

a bat, Phyllostoma) 
Stomoxys calcitrans .... 

Tabanus rjlaucopsis .... 

Crithidia fasciculata, L^ger. 

A Herpetomonad (cf. with H. jaculum) 
[Sergent, E. and E., 1906]. 

Herpetomonads (said to resemble 
Leger's Crithidia) [Ross, 1898 ; 
Christophers, 1901, and others]. 

Herpetomonas bombycis, Levaditi. 

Crithidia campanulata, Leger. 

Leishmania (Piroplasma) donovani. 

Herpetomonads [Ross, 1898 ; Chris- 
tophers, 1901 ; Patton, 1907]. 

Trypanomorpha nociuae (Schaud.) ; 
Crithidia fasciculata ; " Trypano- 
soma" (Herpetomonas) culicis, N., 
M'N., and Torrey ; H. algeriense, 
Sergent, E. and E. ; H. sp., indet. 
[Patton, 1907]. 

H. lesnei, Leger. 

T. brucii ; perhaps T. gambiense. 

(?) T. brucii. 

T. grayi, Novy ; T. tidlochii, Minchin ; 
(?) T. dimorphon, Dutt. and Todd. 

(?) T. brucii ; (?) T. gambiense. 

(?) T. lewisi. 

(?) //. subulata, Leger. 

T. thcileri (probably). 

//. (cf. muscae-domesticae) [Leger]. 

" Trypanosome-like parasites " [Pfeiffer, 

If. muscae-domesticae, Burnett. 

//. jaculum, Leger. 

//. (cf. m.-d.) [Leger]. 

T. lewisi (probably) ; a Herpetomonad 
[Dalfour, 1906]. 

H. sarcophagae, Prowazck. 

//. algeriense, Sergent, E. and E. 

A "Trypanosome" [Durham, 1900]. 

(?) T. equinum ; 
[Gray, 1906]. 
//. subulata, Leger. 

a Herpetomonad 


T. lineola and other sp. . . . (?) T. evaiisi. 

T. tergestimis ..... Herpetomonas (Crithidia) minuta, 


Tanypus sp H. gracilis, Ldger. 

Theicomyxa fusca .. . . . H. (cf. m.-d.} [Leger]. 
"Water-bug" (India) ... A Herpetomonad [Patton, 1907]. 


Ehipicephalus sanguineus, dog-tick " T." christophcrsi, N.. M'N. , and 
(India) Torrey. 


Calobdella punctata .',- . . . T. cotti and T. soleae [Brunipt]. 

Helobdella algira . . . . T. inopinatum [Billet]. 

Hemiclepsis marginata . . . Tpl. varium [Le'ger]. 

H. sp. ...... T. abramis, acerinac, barbi, dani- 


remaki, squalii; perhaps also T. 

barbatulae (?), langeroni, Icucisci, 

scardinii [Brumpt]. Tpl. abramidis 

Piscicola sp. ..... T. barbatulae [Leger] ; Tpl. borreli, 

barbi, guernci, (tytruttae [Brumpt]. 
P. geometra Tpl. borreli ; also other Trypanoplasms 


Pontobdella muricata T. raiae [Robertson]. 

P. sp. ...... T. scyllii [Brumpt]. 


Abyla pentagona, Cucubalus kochii, Trypanophis grobbeni (Poohe). 
Halistemma tergestinum, and Mono- 
phycs gracilis 


I. Relating to the Trypanosomes. 
A. Comprehensive works. 

1. Laveran, A., and. Mesnil, F. Trypanosomes et try panosomiases. Paris (Masson 

et Cie.), 1904. An English edition, translated and considerably enlarged 
and brought up to date by D. Nabarro, has lately been published (Londou, 
Bailliere, Tindall and Cox, 1907, 581 pp., 81 text-figg.). 

2. Liihe, M. Die im Blute schmarotzenden Protozoen. In Mense's Handbuch 

der Tropenkrankheiten, vol. iii. pt. i. (Leipzig, J. A. Barth, 1906), pp. 69- 
268, 3 pis., text-figg. 

3. Woodcock, H. M. The Haemoflagellates. Q.J. Micr. Sci. 1., 1906, pp. 

151-331, 65 text-figg. 


B. List of the more important memoirs cited in the text. (N.B. Full 
references to the existing literature are given in each of the above works.) 

4. Billet, A. Culture d'un Trypanosome de la grenouille chez tine Hirudinee : 

relation atitogenique possible de ce Trypanosome avec tine Hemogregarine. 
O.K. Ac. Sci. cxxxix. p. 574, 1904. 

5. Sur le Trypanosoma inopinatvm . . . et sa relation possible avec les 

Drepanidium. C.R. Soc. Biol. Ivii. p. 161, 16 figg., 1904. 

6. Bradford, J. II. , and Plimmer, H. G. The Trypanosoma brucii, the Organism 

found in Nagana or the Tsetse-fly Disease. Q.J. Micr. Sci. xlv. p. 449, 
2 pis., 1902. 

7. Bruce, D. Reports on the Tsetse-fly Disease or Nagana. Ubombo, Zululand, 

1895 and 1896-; London, 1897 and 1903. 
8. , Nabarro, D., and Greig, E. D. [Reports on Sleeping-Sickness and various 

Animal Trypanosomoses in Uganda.] Roy. Soc. Comm., 1903-1907. 
9. Bruin/it, E. Contribution a 1'etude de 1'evolution das Hemogregarines et des 

Trypauosomes. C.R. Soc, Biol. Ivii. p. 165, 1904. 

10. Sur quelques especes nouvelles de Trypauosomes parasites des poissons 

d'eau douce ; leur mode devolution. Op. cit. Ix. p. 160, 1906. 

11. Mode de transmission et evolution des Trypanosomes des poissons ; 

description de quelques especes de Trypanoplasmes des poissons d'eau douce ; 
Trypanosome d'un crapaud africain. T.c. p. 162, 1906. 

12. Experiences relatives au mode de transmission des Trypanosomes et 

des Trypauoplasmes par les Hirudinees. Op. cit. Ixi. p. 77, 1906. 

13. Role pathogeue et mode de transmission du Trypanosoma inopinatum, 

Ed. et Et. Sergent. Mode d'inoculatiou d'autres Trypanosomes. T.c. 
p. 167, 1906. 

14. - - De 1'heredite des infections a Trypanosomes et Trypanoplasmes chez 

les hotes intermediares. Op. cit. Ixiii. p. 176, 1907. 

15. and Lebailly, C. Description de quelques nouvelles especes de 

Trypanosomes et d'Hemogregarines parasites des Teleosteens marins. 
C.R. Ac. Sci. cxxxix. p. 613, 1904. 

16. Buffard, M., and Schneider, G. Le Trypanosome de la Dourine. Arch. 

Parasitol. iii. p. 124, pis., 1900. 

17. Castellani, A. Trypanosoma and Sleeping-Sickness. Reports S.S. Comm. 

Roy. Soc. i. and ii., 1903. 

18. Danilewsky, . Recherches sur la parasitologie comparee du sang des 

oiseaux. Kharkotf, 1888-1889. 
19. Zur Parasitologie des Blutes. Biol. Centrlbl. v. p. 529 (1885). 

20. Dutton, E. Note on a Trypanosoma occurring in the Blood of Man. Brit. 

Med. Jouru., 1902, ii. p. 881, 1 fig. 

21. and Todd, J. L. First Report of the Trypanosomosis Expedition to 

Senegambia (1902). Mem. Livpl. Sch. Trop. Med. No. 11, 1903. 

22. Franca, C., and Athias, C. Recherches sur les Trypanosomes des Amphibiens : 

I. Les Trypanosomes de la Eana esculenta. Arch. Inst. R. Bact., 
Lisbonne, i., 1906. 

23. Gray, A. C., and Tulloch, F. M. The Multiplication of the Trypanosoma 

gambiense in the Alimentary Canal of Glossina palpalis. Rep. S.S. Comm. 
Roy. Soc. No. 6, p. 282, 1 pi., 1905. 

24. Gruby. Recherches et observations sur une nouvelle espece d'Hematozoaira 

(Trypanosoma sanguinis). C.R. Ac. Sci. xvii. p. 1134, 1843; and Ann. 
Sci. Nat. (3), i. p. 105, 7 figg., 1844. 


25. Hanna, W. Trypanosoma in Birds in India. Q.J. Micr. Sci. xlvii. p. 433, 

1 pi., 1903. 

26. Keyssclitz, G. Ueber Trypanophis grobbcni (Trypanosoma g., Poche). Arch. 

Protistenk. iii. p. 367, 3 figg., 1904. 

27. Generations- und Wirthswechsel von Trypanoplasma borreli, Lav. et 

Mesn. Arch. Protistenk. vii. p. 1, text-figg., 1906. 

28. Koch, A'. Vorlaufige Mittheilungen iiber die Ergebnisse meiner Forschungs- 

reise nach Ostafrika. Deutsch. med. Wocheuschr., 1905, p. 1865, 

29. Ueber den bisherigen Verlauf der deutschen Expedition zur Erforsch- 

ung der Schlafkrankheit in Ostafrika. Op. cit. 1906, Appendix, p. 51 ; 
also 1907, p. 49. Schluss-Bericht. Op. cit. 1907, p. 1889. 

30. Lankester, E. R. On Undulina, the type of a New Group of Infusoria. Q.J. 

Micr. Sci. xi. p. 387, 4 figg., 1871. 

31. - - The Sleeping-Sickness. Quart. Rev., July 1904, p. 113, 7 figg. 

32. Laveran, A. Sur un nouveau Trypanosome des Bovides. C.R. Ac. Sci. 

cxxxiv. p. 512, 1902. 

33. Au sujet de deux Trypanosomes des Bovides du Transvaal. Op. cit. 

cxxxv. p. 717, 5 figg., 1902. 

34. Sur un Trypanosome d'une chouette. C.R. Soc. Biol. Iv. p. 528, 

2 figg., 1903. 

35. Contribution a 1'etude de Hacmamoeba ziemanni. T.c. p. 620, 

7 figg., 1903. 

36. Sur une nouveau Trypauosome d'une grenouille. Op. cit. Ivii. p. 158, 

2 figg.', 1904. 

37. and Mesnil, F. Recherches morphologiques et experimentales sur le 

Trypanosome des rats, Tr. lewisi (Kent). Ann. Inst. Pasteur, xv. p. 673, 

2 pis., 1901. 

38. and Sur les Flagelles a membrane ondulante des poissons (genus 

Trypanosoma, Gruby, et Trypanoplasma, n. gen.). C.R. Ac. Sci. cxxxiii. 
p. 670, 1901. 

39. and Sur la structure du Trypanosome des grenouilles et sur 

1'extension du genre Trypanosoma, Gruby. C.R. Soc. Biol. liii. p. 678, 

3 figg., 1901. 

40. and Sur les Hematozoaires des poissons marins. C.R. Ac. Sci. 

cxxxv. p. 567, 1902. 

41. and Sur quelques Protozoaires parasites d'une tortue d'Asie 

(Damonia reevesii). T.c. p. 609, 14 figg., 1902. 

42. and Des Trypanosomes des poissons. Arch. Protistenk. i. p. 475, 

15 figg., 1902. 

43. and Recherches morphologiques et experimentales sur le 

Trypanosome du Nagana ou maladie de la mouche tse-tse. Ann. Inst. 
Pasteur, xvi. p. 1, 13 figg., 1902. 

44. and Sur un Trypanosome d'Afrique pathogene pour les Equides, 

T. dimorphon, Button et Todd. C.R. Ac. Sci. cxxxviii. p. 732, 7 figg., 

45. Lebailly, C. Sur quelques Hemoflagelles des Teleosteens marins. Op. cit. 

cxxxix. p. 576, 1904. 

46. Lfyer, L. Sur la structure et la mode de multiplication des Flagelles du 

genre Herpetomonas, Kent. C.R. Ac. Sci. cxxxiv. p. 781, 7 figg., 


47. Ltger, L. Sur un Flagelle parasite de 1' Anopheles mnculipennis. C.R. Soc. 

Biol. liv. p. 354, 10 figg., 1902. 

48. Sur quelques Cercomonadines nouvelles ou peu connues parasites de 

1'intestiu des Insectes. Arch. Protistenk. ii. p. 180, 4 figg., 1903. 

49. Sur la morphologie du Trypanoplasma des vairoiis, et sur la structure 

et les affinites des Trypauoplasmes. C.R. Ac. Sci. cxxxviii. pp. 834, 
856, 5 figg., 1904. 

50. Sur les Hemoflagelles du Colitis barbatula, L. ; Trypanosma barbatulae, 

n. sp. ; et Trypanoplasma varium, n. sp. C.R. Soc. Biol. Ivii. pp. 344, 345, 

51. Sur tin nouveau Flagelle parasite des Tabauids. T.c. p. 613, 6 figg., 


52. Sur les affinites de 1' ' Herpetomonas subulata et la phylogenie des 

Trypanosomes. T.c. p. 615, 1904. 

53. Sur la presence d'un Trypanoplasma intestinal chez les poissons. 

Op. cit. Iviii. p. 511, 1905. 

54. Lignieres, J. Contribution a 1'etude de la trypanosomose des Equides 

Sud-Americains connue sous le nom de Mai de Caderas (Trypanosoma 
elmassiani). Rec. Med. Vet. Bull, et Mem. (8), x. pp. 51, 109, 164, 

2 pis., 1903. 

55. Lingard, A. A new Species of Trypanosome found in the Blood of Rats 

(India), etc. J. Trop. Vet. Sci. i. p. 5, 1 pi., 1906. 

56. M'Neal, W. J. On the Life-History of T. lewisi and T. brucii. J. Inf. 

Diseases, i., Nov. 1904. 

57. Minchin, E. A. On the Occurrence of Encystation in Trypanosoma grayi, 

Novy, etc. P. Roy. Soc. Ixxix. B, p. 35, text-figg., 1907. 

58. Investigations on the Development of Trypanosomes in Tsetse-flies, 

etc. Q.J. Micr. Sci. Hi. p. 159, 6 pis., 1908. 

59. , Gray, A. C., and Tulloch, F. At. Glossina palpalis in its Relation to 

Trypanosoma gambiense and other Trypanosomes. P. Roy. Soc. Ixxviii. B, 
p. 242, 3 pis., 1906. 

60. Mitrophanow, . Beitrage zur Kenntniss der Hamatozoen. Biol. Centrlbl. 

iii. p. 35, 2 figg., '1883. 
61; Novy, F. G. The Trypanosomes of Tsetse-flies. J. Inf. Diseases, iii. p. 394, 

3 pis., 1906. 

62. and M'Xeal, W. J. On the Trypanosomes of Birds. Op. cit. ii. p. 256, 

11 pis., 1905. 
63. and - On the Cultivation of Trypanosoma brucii. Op. cit. i. p. 1, 

64. , , and Torrey, H. N. The Trypanosomes of Mosquitoes and 

other Insects. Op. cit. iv. p. 223, 7 pis., 1907. 

65. Patton, W. S. Preliminary Note on the Life-Cycle of a Species of Herpeto- 

monas found in Culex pipiens. B.M.J., 1907, ii. (July 13th). 

66. Plchn, M. Trypanoplasma cyprini, n. sp. Arch. Protistenk. ii. p. 175, 1 pi., 


67. Pricolo, A. Le Trypanosome de la souris. Cycle de developpement des Try- 

panosomes chez le fetus. Centralbl. Bakt., Abt. 1, xlii. Orig. p. 231, 1906. 

68. Prowazek, S. Studien iiber Saugethiertrypanosomen. Arb. kais. 

Gesundhtsa. xxii. p. 1, 6 pis., 1905. 

69. Die Eutwickelung von Herpetomonas, einen mit den Trypanosomen 

verwandten Flagellaten. Op. cit. xx. p. 440, text-figg., 1904. 


70. Rabinowitsch, L., and Kempner, W. Beitrage zur Kenntniss der 

Blutparasiten, speciell der Rattentrypanosomen. Zeitschr. Hyg. xxx. 
p. 251, 1 pi., 1899. 

71. Robertson, M. Notes on Certain Blood-inhabiting Protozoa. Proc. Physic. 

Soc. Edinb. xvi. p. 232, 2 pis., 1906. 

72. Studies on a Trypanosome found in the Alimentary Canal of Ponlob- 

della muricata. Op. cit. xvii. p. 83, 4 pis., 1907. 

73. Rogers, L. The Transmission of the Trypanosoma eransi in India by Horse- 

flies, etc. Proc. Roy. Soc. Ixviii. p. 163, 1901. Also see B.M.J., 1904, 
ii. p. 1454. 

74. Ross, 11. Notes on the Parasites of Mosquitoes found in India between 1895 

and 1899. Journ. Hyg. vi. p. 101, 1906. 

75. Schaudinn, F. Generations- uud Wirthswechsel bei Trypanosoma und 

Spirochaeta. Arb. kais. Gesundhtsa. xx. p. 387, text-figg., 1904. 

76. Sergent, E. and E. Sur un Trypanosome nouveau parasite de la grenouille 

verte. C.R. Soc. Biol. Ivi. p. 123, 1 fig., 1904. 

77. Hemamibes des oiseaux et moustiques. Generations alternantes de 

Schaudinn. Op. cit. Iviii. p. 57, 1905. 

78. Sur des Trypanosomes des chauves - souris. T.c. p. 53, 2 figg., 


79. Sur un Flagelle" nouveau de 1'intestin des Culex et des Stegomyia, 

Herpetomonas algeriense. Op. cit. Ix. p. 291, 1906. 

80. Stuhlmann, F. Beitrage zur Kenntniss der Tsetsefliegen (Gl. fusca and Gl. 

tachinoides). Arb. kais. Gesundhtsa. xxvi. p. 83, 4 pis., 1907. 

81. Swingle, L. D. Some Studies on Trypanosoma lewisi. Trans. Amer. Micr. 

Soc. xxvii. p. Ill, 1 pi., 1907. 

82. Thiroux, . Sur un nouveau Trypanosome des oiseaux. C.R. Ac. Sci. 

cxxxix. p. 145, 5 figg., 1904. 

83. Recherches morphologiques et experimentales sur les Trypanosoma, 

paddae. Ann. lust. Pasteur, xix. p. 65, 1 pi., 1905. 

84. Recherches ... sur Trypanosoma duttoni, Thiroux. T.c. p. 564, 

1 pi., 1905. 

85. Voges, 0. Mai de Caderas. Zeitschr. Hyg. xxxix. p. 323, 1 pi., 1902. 

86. Wasielewsky and Senn, G. Beitrage zur Kenntniss der Flagellaten des. 

Rattenblutes. Op. cit. xxxiii. p. 444, 3 pis., 1900. 

II. Relating to the ' ' Leishman- Donovan- Wright " Bodies. 

87. Christophers, S. R. Reports on a Parasite found in Persons suffering from 

Enlargement of the Spleen in India. Sci. Mem. India, Nos. 8, 11, 15, 

88. Donovan, C. Human Piroplasmosis. Lancet, 1904, ii. p. 744, 1 pi. 

89. James, S. P. Oriental or Delhi Sore. Sci. Mem. India, No. 13, 1905. 

90. Laveran, A., and Mesnil, F. Sur un Protozoaire nouveau (Piroplasma 

donovani, Lav. et Mesn.), etc. C.R. Ac. Sci. cxxxvii. p. 957, 17 figg., 
1903 ; and op. cit. cxxxviii. p. 187, 1904. 

91. Leishman, W. On the Possibility of the Occurrence of Trypanosomosis in 

India. Brit. Med. Journ. 1903, i. p. 1252, 2 figg. ; see also op. cit., 
1904, i. p. 303. 

92. and Statham. The Development of the Leishman Body in 

Cultivation. Journ. Army Med. Corps, iv. p. 321, 1 pi. 2 figg., 1905. 


93. Patton, W. S. Prelim. Report on the Development of the Leishman- 

Donovan Body in the Bed-Bug. Sci. Mem. India, No. 27, 1907. 

94. Rogers, L. On the Development of Flagellated Organisms . . . from the 

Spleen Protozoic Parasites of Kala-Azar. Q.J. Micr. Sci. xlviii. p. 367, 
1 pi., 1904. 

95. Further Work on the Development of the Herpetomonas of Kala- 
Azar . . . from the Leishmau-Donovan Bodies. Proc. Roy. Soc. Ixxvii. B, 
p. 284, pi. 7, 1906 ; see also Lancet, 1905, i. p. 1484. 

96. floss, It. A New Parasite of Man. Thorn pson-Yates Lab. Rep. (5), 2, 

p. 79, 1 pi., 1904. 

97. Wright, J. H. Protozoa in a Case of Tropical Ulcer (Delhi Sore). Journ. 

Med. Research, Boston, x. p. 472, 4 pis., 1903. 

C. Relating to the Spirochaetae. 

98. Certes, A. Note sur les parasites et les commensanx de 1'huitre. Biol. 

Soc. Zool. France, vii. p. 347, 1 pi., 1882 ; see also op. cit. xvi. pp. 95 and 
130, 1891. 

99. Laveran, A., and Mesnil, F. Sur la nature bacterienne du pretendu 

Trypauosome des huitres, " T." balbianii. C.R. Soc. Biol. liii. p. 883, 

100. Perrin, W. S. Researches upon the Life -History of " Trypanosoma " 

balbianii (Certes). Arch. Protistenkunde, Jena, vii. p. 131, 2 pis., 

101. Krzysztalowicz, F., and Siedlecki, M. Contribution a 1'etude de la struc- 

ture et du cycle evolutif de Spirochaeta pallida, Schaud. Bull. Ac. 
Cracovie, 1905, p. 713, 1 pi. 

102. Schaiulinn, F. Zur Kenntniss der Spirochaeta pallida. Deutsch. med. 

Wochenschr. No. 42, 1905, p. 1665 ; see also t.c. p. 1728 (gen. 
Treponeina proposed). 

103. and Hoffmann, E. Vorlaufiger Bericht ueber das Vorkommen 

von Spirochaeten in syphilitischen Krankheitsproducten. Arb. kais. 
Gesundhtsa. xxii. p. 527, 1905. 



THIS genus is represented by two species. C. labyrinthuloides was dis- 
covered by Archer in pools in moorland country in Ireland and 
described by him in 1875 (1). It has subsequently been investigated 
by Geddes (2) in material supplied by Archer ; and by Hieronymus (3), 
who found it in the Riesengebirge and elsewhere in Germany. 0. mon- 
tana was first described by Lankester (5) and obtained by him in 
Sphagnum swamps in Switzerland, and has since been investigated by 
Penard (6). 

Two main phases of the life-history are in many respects well 
known a free active stage, with pseudopodia more or less extended, and 
a (much commoner) encysted stage ; and we now have evidence, though 
it is still incomplete, of stages of multiplication by fission and of spore- 

Chlamydomyxa unites in a remarkable manner the holophytic and 
holozoic modes of nutrition. The protoplasmic body is crowded with 
chromatophores, by means of which it is able to increase largely in size in 
the encysted state ; but it is also able, in its active phase, to engulf and 
to digest animal and vegetable organisms. 

The body consists of hyaline protoplasm containing nuclei, chromato- 
phores, and small refracting bodies the "oat-shaped corpuscles" of 
Lankester. In the encysted condition it may form a globular mass, 
measuring, when fully grown, 60-90 p in diameter in C. labyrinthuloides, 
the cysts of C. montana being a little smaller. 

The nuclei (Fig. 1, a, b, and d) vary from 1 '5 to 3 //, in diameter. They 
are generally evenly distributed through the protoplasm, and they increase 
in number with its growth. In the large cysts of C. labyrinthuloides 
there may be as many as 32 or more ; in C. montana, according to Penard, 
100 or more. They contain a nucleolus or group of nucleoli at the 
centre, and there are indications of a nuclear . reticulum at the periphery. 
Their mode of division is, according to Hieronymus, intermediate between 
mitosis and amitosis. In life they are visually hidden by the chromato- 
phores, and thus escaped the notice of the earlier observers. 

The chromatophores are oval bodies varying in size up to 3 //, (C. mon- 
tana) and 5'5 /A (G. labyrinthuloides, Fig. 1, d). They consist of coloured 

1 By J. J. Lister, M.A., F.R.S., Fellow of St. John's College, Cambridge. 




and colourless tracts, which are apparently differently distributed in the two 
species. The colour varies from grass-green to olive-green, yellow, and 
brown, and is dependent on the presence, in varying proportions, of 
chlorophyll and of a yellow-brown colouring matter (? diatomin). They 


PIG. 1. 

Chlamydomyxa labyrinthuloides. a and 6, cysts from leaf-cells of Sphagnum, constricted by 
the characteristic annular bands of the latter, from stained preparations showing the chromato- 
phores and nuclei, x 620. c, end of a living cyst, treated with weak methylene blue solution. 
The chromatophores are shaded. The nuclei are not seen, x 5000. d, nuclei highly magnified ; 
c, /, living chromatophores ; g, chromatophore after treatment with Flemming's fluid and 
fuchsin ; h, oat-shaped corpuscles ; e-h x about 10,000. (After Hieronymus.) 

appear to multiply by binary fission (Fig. I,/). The absence of a cellulose 
envelope and of a nucleus, as well as other characters of the chromatophores, 
prevent their being regarded as symbiotic algae. As a degeneration 
product, and especially under the influence of bright sunlight, the 
colouring matter breaks down, producing a red or brown fatty substance 
^lipochrome) which accumulates in drops in the interior of the cysts, and, 


by its colour, reveals the presence of Chlamydomyxa when it is present in 
abundance on the vegetation of a pool. 

The oat-shaped corpuscles ("spindles" of Archer, "physodes" of 
Hieronymus) are shining, highly-refracting bodies, homogeneous or faintly 
laminated, of a pale bluish tint and semifluid consistence (Fig. 1, h). 
They are round or oval in shape, but become longer (oat-shaped) when 
drawn out on the pseudopodial filaments. They vary in size up to about 
2 p. in length. As regards composition, Hieronymus identifies them with 
phloroglucin, a member of the aromatic series which occurs in the 

When Chlamydomyxa was discovered the resemblance between these 
bodies, held in the expanded, stiff pseudopodial network (Fig. 3 (2)) and 
the nucleated units of the associations of Labyrinthula, suggested the view 
that they might be of similar nature, although nothing of a nuclear 
character could be revealed in the corpuscles by stains, and they are, 
moreover, much smaller than the units of Labyrinthula. The evidence 
which we now have as to the nuclei of Chlamydomyxa, and as to the 
chemical nature of these bodies, prevents our acceptance of this view. 
They are probably to be regarded as reserve food material (possibly in 
relation with the metabolism of cellulose) stored in a granular form. 

Crystals of oxalate of lime, formed doubtless in the katabolic pro- 
cesses, are also present in the cell-fluids, and they may be crowded in 
vacuoles of the encysted animal, to be expelled when it emerges. 

The cysts of Chlamydomyxa are found in great abundance within the 
large cells of the leaves of Sphagnum, or between the cells of other 
aquatic plants (Hypnum, Eriocaulon, cotton-grass, etc.). They may also 
be found on the surface of these and other submerged bodies. 

They are invested by a cellulose envelope, often consisting of several 
laminae added one within another, and the investment appears to be of a 
plastic consistency, expanding with growth so as to cover large protrusions 
of the cyst which extend through apertures in the cell-wall, and it may 
close in about portions which are withdrawn from deeper recesses of the 
plant tissue. Considerable growth of the protoplasmic body may occur 
in the encysted condition, a result dependent on the holophytic nutrition 
brought about by the agency of the chromatophores. The youngest 
cysts found in a Sphagnum leaf are very small and contain a single 
nucleus. As they increase in size and become limited by the walls of the 
elongated leaf-cells they grow in length (Fig. 1, a and 6). The cysts may 
finally break through the wall of the cell and project in lobate prominences 
to the exterior. The activities of the encysted organism do not, however, 
result in uniform growth, for many cysts have shrunken contents, and 
have formed a fresh wall separate from the original one, and in the 
space between the envelopes groups of the red oil- globules referred to 
above may lie, discharged before the inner wall was secreted. Moreover, 
the contents of a cyst may undergo division within the envelope into two 
or more parts, and each part then forms a wall of its own. 

When the cysts are fully grown and favourable conditions occur, an 
aperture is formed in the envelope, presumably by the solvent action of 
the protoplasm on the cellulose, and the contents emerge in the free state. 


The accounts of the behaviour of the organism in the free state differ 
considerably and are not easy to reconcile. 

In G. labyrintJmloides, as described by Archer (cp. his figure in the 
Q.J.M.S. vol. xv. Plate vi., from which Fig. 3 (2) is taken), the proto- 
plasmic body was still partially contained in the cyst. Extending 
through the aperture, it was produced into a dendriform system of 
branches, diminishing in thickness. From the ends and sides of the 
branches filiform hyaline pseudopodia of small but uniform thickness 
reach far out into the water. The chromatophores are not seen in 
relation with the filaments, but these are plentifully beset with the oat- 
shaped corpuscles. The latter are drawn out in the direction of the 
filament, and slowly travel along it in one direction or the other. The 
filaments are sparingly branched ; whether or not they anastomose, 
observers are not agreed. They have a " stiff but flexible " (Penard) 
consistency. Lankester is inclined to regard the filaments as " inert 
products of the metamorphosis " of the protoplasm, over which a 
" delicate varnish " of hyaloplasm extends, investing the corpuscles and 
carrying them along in its flow. Yet the whole system of these 
remarkable pseudopodia can be rapidly withdrawn into the general mass 
when the animal is disturbed. Hieronymus describes a peculiar fibrous 
arrangement of the protoplasm even in the encysted state, which may be 
in relation with the peculiar characters of the extended filaments (Fig. 1, c. 
Note the linear arrangement of the oat-shaped corpuscles). 

Contractile vacuoles abound in the extended protoplasmic body. 
Their period probably varies with its activity. In 0. montana Penard 
finds it to be very slow. 

In the active condition C'hlamydomyxa is able to engulf and digest 
algae, desmids, Peridinidae, etc., and outlying masses of protoplasm may 
be seen (Fig. 3 (2)) accumulated about such food-bodies. 

The accounts of the active phase of 0. montana agree, on the whole, 
with Archer's observations of G. labyrinthuloidcs, except that in the 
former species the protoplasm, on emerging, completely quits the old cyst- 
wall and lies free in the water as a mass of constantly changing shape. 
It may be more or less spherical or drawn out into a ribbon, attaining a 
length of 300 p, (Penard). A definite hyaline ectoplasm is also present. 
(Cp. the figures of this species given by Lankester, Q.J.M.S. 
vol. xxxix. Plates xiv. and xv.) In it, moreover, the yellow colouring 
matter of the chromatophores usually predominates over the green. 

According to most observers, the free state of the organism would 
appear to end, after lasting at least " several hours," by the withdrawal of 
the extended protoplasm and the re-encystment of the whole animal. 
Hieronymus differs considerably from other observers in his account of 
the free state. He has also seen the contents emerge from a cyst of 
C. labyrinthuloides, assume an irregular amoeboid form, and ingest food 
"auf thierische Weise" ; but it is remarkable that he has never, during 
the twelve years over which his observations have extended, seen the long 
filamentary pseudopodia protruded in the manner which has, in both 
species, attracted attention. The nearest approach to such filaments 
which he has seen were those of a small specimen suspended free in the 


water and emitting long pseudopodia on all sides (3 ; Plate ii. Fig. 25). 
After ingesting food the animals were found by Hieronymus to encyst on 
the surface of plants, and he states that division of the nuclei follows the 
encystment. But in the majority of cases a different process was 
observed to follow the emergence from the encysted state. The proto- 
plasm puts out short pseudopodia and divides up forthwith, by successive 
repartition or by simultaneous division, into small uninucleate amoebae, 
the products of division being equal in number to the nuclei contained 
in the original cyst. The division into the ultimate products is usually 
complete in a few minutes from the emergence of the protoplasm. The 
small amoebae so found may creep about and ingest small algae or 
bacteria before passing into the encysted form. While this is the usual 
course, Hieronymus describes cases in which the process of division ceased 
after one or two partitions had occurred, and was followed by a stage of 
feeding and subsequent encystment. Further evidence of such cases 
would be desirable, and it seems possible that two separate phases of the 
life-history may have been here confused ; but it is clear that the fission 
of the multinucleate body into uninucleate products represents a phase of 
reproduction comparable with that which occurs in many other protozoan 
life-histories, and of which we had no previous evidence in Chlamydomyxa. 

Spore-Formation. The process of spore-formation has been most fully 
observed by Penard in G. montana, 1 but stages of it have been seen by 
Archer and Hieronymus in C. labyrinthuloides. The contents of an 
encysted form are segregated by simultaneous fission into a number 
(20 to 40) of equal (Fig. 2, a) (? sometimes only sub-equal (Fig. 2, 6)) 
divisions. These are at first continuous with their neighbours by proto- 
plasmic strands (3 ; Plate i. Fig. 7), but later they separate into bodies 
which become spherical and each secretes a cellulose wall. They are 
liberated by the opening of the cyst (in a manner not observed). Penard 
finds that these secondary cysts, or spores (Fig. 2, c), as we may call them, 
measure in G. montana 18 [L in diameter, and that each contains two 
nuclei lying opposite one another in a meridian of the sphere. 2 In some 
cases the contents of the spores were found to have emerged as naked 
masses of protoplasm, containing the chromatophores and refracting 
corpuscles characteristic of the species. Each acquired a flagellum (or two 
flagella ?) about equal to the body in length (Fig. 2, d), and for some 
moments ("pour quelques instants") was actively motile. Some of these 
flagellate bodies appeared to possess one nucleus, others two or even 
three, and there was an indication of their fusion in pairs (" lorsque les 
petits flagellates viennent & se rencontrer, ils peuvent se fusionner en un 
seul," p. 331). Some continued to show a slow movement for twenty- 
four hours, but ultimately they died under the cover-slip. 

It would be premature at present to make any dogmatic statement as 

1 It was only for a few days that Penard succeeded in observing this stage in the 
life-history. It occurred in March, in the neighbourhood of Geneva. 

2 Penard's account of the subsequent history of these bodies is of great interest, 
but, owing to the sparseness of his rnaterial and the rapidity of some of the events, 
he was unfortunately not able to observe the stages with precision. With this 
reserve, an outline of his results is here given. 



to the course of the life-history of Chlamydomyxa. The observations 
of Penard suggest that the flagellulate bodies hatching from the spores 
are gametes, which proceed to conjugate with one another, though the 
existence of two nuclei in the spores requires explanation. If this is the 
case, we have, as in Trichospliaerium and many other Protozoa, a life-cycle 
in which a sexual phase recurs in a series of generations reproducing by 

With regard to the affinities of Chlamydomyxa, we have seen that the 
resemblance to Labyrinthula turns out to be in part at least misleading. 


FIG. 2. 

CMart >/<'">/"'. a. Early stage of spore-formation in C. montana. The contents of a cyst 
have become divided up into young spores ; b, a cyst of C. labyrinthuloides, with mature spores, 
x 200 ; c, a single spore of C. montana, showing two nuclei ; d, flagellate body hatched from 
a spore. ('<, <, ami il after Penard ; 6 after Archer.) 

We are unable to agree with Penard that it is allied to the Mycetozoa, 
for there is no evidence that the protoplasmic masses are plasmodia in 
the true sense of the term. It appears that the most satisfactory position 
to assign to it, in the present preliminary stage of our knowledge of life- 
liistories, is as an isolated rhizopod, containing chromatophores, which 
may be provisionally placed in the neighbourhood of the freshwater forms 
with filose pseudopodia which, in this work, are included in the Order 
Gromiidea of the Foraminifera (see p. 283). In the possession of many 
nuclei it resembles Trichosphaerium among the Rhizopoda Lobosa. 


1. Archer, W. On Chlamydomyxa labyrinthuloides, nov. gen. et sp., a New 
Freshwater Sarcodic Organism. Quart. Journ. Micr. Sci. N.S. xv. 
(1875), p. 107. 


2. Gcddes, P. Observations on the Resting State of Chlamydomyxa laby- 

rinthuloides, Archer. Ibid. xxii. (1882), p. 30. 

3. Hieronymus, G. Zur Kenntniss von Chlamydomyxa labyrinthuloides, 

Archer. Hedvvigia, Bd. xxxvii. (1898), p. 1. 

4. Jenkinson, J. W, Abstract and Review of the above paper by Hieronyimis. 

Quart. Journ. Micr. Sci. N.S. xlii. (1899), p. 89. 

5. Lankester, E. Ray. Chlamydomyxa monta'iia, n. sp., one of the Protozoa 

Gyranomyxa. Quart. Journ. Micr. Sci. xxxix. (1896), p. 233. 

6. Penard, E. Etude sur la Chlamydomyxa montana. Arch. f. Protistenkunde, 

Bd. iv. Heft 2 (1904), p. 296. 


The members of this genus consist of associations of nucleated proto- 
plasmic units ("amoebae" of Zopf, "spindles" of Cienkowski) joined in 
a network of sparingly branched and anastomosing threads. They are 
met with in a diffuse or aggregated condition, and, as the result of 
drying, the units pass into a condition of encystment, from which they 
hatch out in the form of the amoeboid units. 

Two marine species were described in 1867 by Cienkowski (1), who 
found them on algae growing on wooden piles in the harbour of Odessa : 
L. vitellina, Cienk., in which the protoplasmic units contain a yellow or 
orange colouring matter ; and L. macrocystis, Cienk., in which the units 
are larger and colourless. Zopf (4) in 1892 described a freshwater 
form very similar to L. macrocystis, parasitic on the alga Vaucheria. 
He named it L. cienkowskii, Zopf. 

In the marine forms the system of connecting threads appears to have 
a remarkably firm and rigid consistency, and Cienkowski describes the 
movement of the units along the threads, as though the latter were 
peculiarly differentiated structures ; but from Zopf's description of L. 
cienkowskii it can hardly be doubted that they are pseudopodial in nature. 
Zopf observed them to be slowly protruded from a mass of units, and to 
be withdrawn, to move slowly from side to side, and to fuse with their 
neighbours. He also describes the passage of food - granules along 

The units are without a limiting membrane and contain a single 
nucleus, with a nucleolus. When drawn out in the expanded condition 
of the organism they are generally spindle-shaped (Fig. 3 (3)), but they 
may present processes in three directions (Fig. 3 (4)). In the aggregated 
condition the units are round or oval. Those of L. macrocystis measure 
18-25 fj, in long diameter, those of L. vitellina and L. cienkowskii about 
1 2 /*. The protoplasm is granular, and in L. vitellina contains a yellow 
or orange fatty pigment, soluble in alcohol. A small vacuole is usually 
present, but it is not stated that it is contractile. 

The whole organism, or a part of it, is often found in the aggregated 
condition (Fig. 3 (5)), and the marine species may thus form masses 
measuring a millimetre or so in diameter. The main aggregate is 
described by Cienkowski as invested, in L. vitellina, by a " cortical sub- 
stance" (neither protoplasmic nor of the nature of cellulose) through 


which the filaments are protruded, but this was not seen in the peripheral 
aggregates of this species, nor at all in the active condition of the other 

Labyrinthula is actively parasitic on the algae which it infests, 
breaking down the contents of the cells into a granular mass. 

As the result of drying, the organism passes into a condition of 
encystment. The units became closely aggregated and each secretes a cyst- 
wall, which is double in L. cienkowskii. A firm common envelope may 
now be formed (in L. macrocystis, Fig. 3 (5), but not in other species) in 
which the encysted units are embedded. 

The behaviour of the encysted unit appears to vary in the different 
species. In L. cienkowskii Zopf describes and figures the emergence of a 
single mass from the cyst. In the other species, Cienkowski found that the 
contents divided into four within the cyst (Fig. 3 (6 and 7)). Zopf observed 
the protrusion of one or two long pointed pseudopodia, on hatching, and 
the final emergence of the protoplasmic mass from the cyst, which was 
left empty. From the fact that on one occasion three empty cases were 
found with three units in their neighbourhood, and that these were in 
connection by their pseudopodia, Zopf concludes that the hatched units 
join with one another to start a fresh association. 

Zopf regards the association of units of Labyrinthula as representing 
a stage in the formation of a plasmodium intermediate between the true 
plasmodium of the Euplasmodida (cf. p. 43), in which there is a complete 
fusion between the protoplasmic bodies of the uniting amoebulae, and the 
pseudoplasmodium of the Sorophora, in which the amoebulae, aggregating 
before spore-formation, come into apposition but maintain their distinct- 
ness (p. 60). This intermediate form he would distinguish as a Thread- 
-plasmodium (Fadenplasmodium). 

The propriety of this view seems far from clear. We are familiar 
with many cases among Protozoa in which an association of individuals, 
a. colonial organism, is formed by the successive multiplication of the 
units, whose offspring remain in connection by protoplasmic processes 
(Colonial Radiolaria, Volvox, Mikrogromio), and the higher animals and 
plants are often regarded as such colonial organisms, in modified 

That an increase in the number of units in the associations of Laby- 
rinthula occurs by binary fission of the units is abundantly clear. It is 
true that it appears probable, from Zopfs observation above quoted, that 
a fusion may occur in Labyrinthula (though it was not actually observed) 
between the pseudopodia of individuals recently emerged from the 
encysted state ; but a parallel to this process may be found in the 
fusion of the protoplasmic masses emerging from the cysts of the 
sclerotial condition of the Mycetozoa on revival of activity (cp. p. 50). 
There are fair grounds for regarding the fusion of the amoebulae 
by which the Mycetozoan plasmodium takes its origin (in the Euplas- 
modida) as a part, at any rate the plastogamic part, of a sexual union of 
which the final, karyogamic, stage is deferred. It would not be sug- 
gested that the fusion after the sclerotial stage is a repetition of this 
process in the Mycetozoa, and we may well hesitate, in the present 


FIG. 3. 


fragmentary state of our knowledge of Labyrinthula, to accept the conclu- 
sion that the (inferred) fusion between the pseud opodia after encystment 
represents this important event in its life-history. 

We are therefore inclined to regard Labyrinthula as a colonial 
organism of which the units remain in connection by their pseudopodia. 
As the result of drying they may pass into the encysted stage, in which 
they are isolated from their fellows by the cyst-walls. It appears prob- 
able, from Zopfs observation, that, on resuming activity, they may 
again unite with their fellows to form a colony. Other stages of the 
life-history are at present unknown to us. 

With Labyrinthula Zopf associates the genus Diplophrys (Archer), 
Cienk. The species named Diplophrys stercorea by Cienkowski (2) is a 
colonial organism, with simple thread-like pseudopodia, living on horse- 
dung. It can hardly belong to the same genus as Diplophrys Archeri 
(Barker), with ramifying pseudopodia and a distinct though membranous 

FIG. 3. 

2. CMamydomyxa Ifihyrinthuloldes, Archer. The animal in the free state partially emerged 
frcnn the many-layercil cyst. A small encysted mass is seen at c between the envelopes of the 
latter. At o and elsewhere in the main body of the protoplasm, as well as in outlying portions, 
invested food particles are shown. The oat-shaped corpuscles are seen on the stiff extended 
filaments, x about 150. (From Lankester, after Archer.) 1 and 3, I.abi/rinthulrt riteltiiw, 
C'ienk. 1, a colony crawling upon an alga. The units are partly aggregated, partly extended 
on the network of stiff extended pseudopodia. x about 120. 3, part of the network, x about 
250. At p and p 1 several units have fused into a common mass ; , s, units which have assumed 
the spherical shape and are stationary. 4-7, Labyrinthula macrocystis, Cienk. 4, a single unit 
giving out three pseudopodia ; n, its nucleus ; x 320. 5, a group of encysted units invested in 
a tough secretion, x about 250 ; f> and 7, encysted units the contents of which have divided 
into I'our, x about 320. (From Lankester, after Cienkowski.) 

test. Both forms, together with Labyrinthula and Chlamydomyxa, may 
provisionally be regarded as related in one direction to outlying members 
of the Gromiidea, here included in the Foraminifera, and in others to the 
Heliozoa and the Proteomyxa. The grounds for regarding the two latter 
genera as especially related have vanished in the light of fuller knowledge. 


1. Cienkowski. Ueber den Ban u. Entwickelung der Labyrinthnleen. Arch. 

f. inikr. Anat. Bd. iii. (1867), p. 274. 

2. Ueber einige Rhizopoden und vevwandten Organismen. Ibid. Bd. 

xii. (1876), p. 44. 

3. Lankester, E. II. Article "Protozoa" (Class Labyrinthulidae). Encyclo- 

paedia Britannica, 1891. 

4. Zopf, jr. Zur Kenntniss d. Labyrintlmleen, eine Fain. d. Mycetozoen. 

Beitr. zur Phys. u. Morphologic niederer Organismen, Heft 2 (1892), 
p. 36, and Heft 4 (1894), p. 60. Leipzig. 



THE organisms that are now included in this family were formerly 
regarded as Porifera, and several of them were described in 1889 by 
Haeckel in the " Challenger " volume xxiii., on the deep-sea Keratosa. 1 In 
the year 1892, Goes (1) described "a peculiar arenaceous Foraminifer 
from the American tropical Pacific" as Neusina agassizii, which Hanitsch 
in the following year proved to be identical with Haeckel's deep-sea 
Keratose sponge Stannophyllum zonarium. We are indebted to Schultze 
(2) for an exhaustive treatise on these genera, and the more definite 
proof that they are not sponges, but probably related to the Foraminifera. 
They are spherical or disc-shaped (Psammetta), fan-shaped (Stannojihyllum, 
Fig. 1), or dendritic (Stannoma) bodies of about 20 mm., more or less, in 

diameter or height, and of a fibrous, spongy 
texture. They have been found at depths 
of from 550 fathoms to 3000 fathoms in 
the Indian, Atlantic, and Pacific Oceans. 

They consist of a plexus of thin-walled 
tubes, some of which open on the surface, 
and the meshes of the plexus contain a 
large number of foreign bodies (xenophya), 
such as the shells of Radiolaria, Foramin- 
ifera, spicules of sponges, and grains of sand. 
The tubes contain either a large number 
of dark olive-brown bodies, the sterkomata, 
or else a multinucleated plasmodium con- 
taining numerous clear solid bodies called 
the granellae. The sterkomata are remark- 
ably resistant to strong acids and alkalis, and they often contain fragments 
of radiolarian and foraminiferan shells. They are regarded by Schultze as 
of the nature of the faecal balls such 'as are found in other Foraminifera 
(Gromia, Saccamina, etc.). The tubes containing the sterkomata (Ster- 
komarium) are probably continuous with the tubes containing the granellae 
(granella'rium). The granellae are about 1-2 /x in diameter, and are mainly 
composed of barium sulphate. The nuclei which occur in the plas- 
modium of the granellariurn are very numerous, and usually scattered 

FIG. i. " 

Stannophyllum zonariiim, Haeck. 
x . (After Schultze.) 

1 Cf. A Treatise on Zoology, Part II., 1900, p. 154. 



irregularly among the granellae. In some cases (Fig. 3) aggregations of 
nuclei with an investing portion* of the protoplasm become separated from 


FIG. 2. 

Section through the middle layer of J'srnnminn glubigfrina, Haeckel, showing the plexus of 
tubes containing a multinucleated plasmodium. At o, a are seen some of the foreign bodies 
(xenophya) associated with the organism ; s, s, tubes of the sterkoinarium ; g, g, tubes of the 
granellarium. (After Schultze.) 

the plasmodium, and these break up into swarm-spores, which Schultze 
regards as possibly gametes. 

In the family Stannomidae there are found, in addition to the tubes- 
already mentioned, many fine skeletal fibres called the " linellae," which 
form a plexus in the interstices of the other 
parts of the organisms. 

In the absence of any information con- 
cerning the early stages of development, or 
of the character of the pseudopodia in the 
members of this family, it is difficult to 
assign to them their proper systematic 
position. The Foraminiferan genus Poly- 
trema and some of its allies liave the same 
habit of incorporating into their substances 
sponge spicules and other foreign bodies, and 
they also lose at an early stage of develop- 
ment the external evidence of the chambered 
condition, and assume dendritic forms. 
Moreover, in Polytrema we find, in addition 

to the calcareous skeleton, a system of are breaking up into spores, 
horny or chitinous tubes which have some 

resemblance to the tubes of the Xenophyophoridae. In the absence of a 
calcareous "skeleton the family differs from all the higher and more 
differentiated families of Foraminifera, but nevertheless the affinities of 
the family are greater \vith this class than with any other Protozoa. 

FIG. 3. 

Diagram of the granellar region- 
of a Xenophyophorid, showing the 
nuclei, n, n, and granellae, g, g, of 


The Xenophyoplioridae may therefore provisionally be placed in the 
Class Foraminifera. 


Sub-Family PSAMMIXIDAH-. Without linellae. Not flexible. Genera 
Psammetta, F. E. S. ; Psammina, Haeck. ; Cerelasma, Haeck. ; Holo- 
psamma, Carter ; Psammopemma, Marshall. 

Sub-Family STANNOMIDA. With linellae. Body flexible. Genera 
Stannoma, Haeck.; Stannophyllum, Haeck. (Fig. 1); Stannarium, Haeck. 


1. Goes. Ncusina agassizi. Bull. Mus. Harvard, xxiii., 1892, p. 19f. 

2. Schultze, F. E. Die Xenophyophoren. " Valdivia" ExpeJ. xi., 1905. 

3. "Siboga" Exped. Mon. iv. bis, 1906. 

4. Bull. Mus. Harvard, li. 6, 1907. 


Figures given in thick type refer to the systematic position. 
f. refers to an illustration. 

Abyla pentagona, 249 
Acautharia, 94, 102, 106, 

113, 145 

Acanthochiasma, 146 ; A. 
cruciala, 146 ; A. fusi- 
forme, 145 ; A. krohnii, 

145 ; A. rubescens, 143 
Acanthochiasmidae, 146 
Acanthocystis, 21, 24, 28, 

29, 34, 119 ; A.aculeata, 

16/., 27/., 28/. ; A. 

italica, 34 ; A . marina, 

34 ; A . simplex, 34 ; A . 

spinifera, 23 ; A. tnr- 

facea, 23 

Acanthodinium, 187 
Acanthometra sicula, 143 
Acanthometrida, 113, 145 
Acanthometron, 123, 146 ; 

A. bifidum, 137/. ; A. 

Claparedei,l05f. ; A. pel- 

lucidum, 118/., 146 
Acantfwnia, 146 ; A. ligur- 

ina, 146 ; A. miilleri, 

146 ; A. tetracopa, 127, 
128/., 132/. 

A cant/ion id ium, 146 ; ^4. 

echinoides, 146 ; .4. ^Z- 

lidum, 146 
Acaiithoniidae, 146 
Acanthophractida, 146 
Acrasiae, 39 

. lr.V".v/,9, 65 

Actineliida, 145 
Actinelius, 145 ; .1. ^'/'- 

pureus, 145 
Actinolophus, 15, 23, 28, 

Actinomma, 127 ; .4. as&r- 

acanthion, 103/. 
Actinomonas, 165 
Actinophrys, 18, 19, 21, 

29, 30, 33, 39 ; vl. soZ, 

15, 16/., 21 f. 

Actinosphaeridium, 33 

Actinosphaerium, 21, 22, 
23, 25, 26/., 29, 30, 32, 
33,48,86, 87; .1. arach- 
noideum, 23 ; A. Eich- 
horni, 14/., 22 ; A. im- 
patiens, 10 f. 

Actissa, 104, 110, 144 

Aethalia, 56 

akaryote, 1, 2 

Alwisia, 63 

Amaurochaetaceae, 63 

Amaurochaete, 63 ; -I. ati-<>, 

Amaurochaetineae, 62 

Amaurosporales, 61 

Amoeba, 2, 69, 77 ; A. 
binucleata, 73, 79 ; A. 
buccalis, 84 ; ^1. crystal- 
ligera, 73, 78 ; ^1. dof- 
leini, 71 ; ^1. fluida, 
78; ^1. guttula, 78/.,79; 
yl. hyalina, 73 ; .4. Aar- 
tulisi, 84 ; ^4. Umax, 69, 
70, 73, 77/., 79, 83 ; .4. 
pilosa, 68 ; .4. proteus, 
73, 74/., 77, 78/., 79 ; 
.4. radiosa, 79 ; -4. rote- 
<on'a, 195 ; ^4. terricola, 
68 ; .4. urogenitalis, 84 ; 
^4. verrucosa, 78f.; A. 
villosa, 79 ; .4. vorax, 
78 /. 

yliftoeda (marine forms), 78 

Amoebophrya, 105 /., 123 

Amoebulae in Heliozoa, 29 ; 
in Lobosa, 76, 77 ; in 
Mycetozoa, 42, 59 ; in 
Proteomyxa, 4, 5 

A iiijiliiiliniuui, 183 

Amphilonche, 123, 146 ; 
.1. atlantica, 137/. ; .4. 
belonoides, 146 ; Jl. ww-s- 
sanensis, 103/. 


Amphilouchidae, 146 
Amphinwiias, 168 
Amphisolenia, 187 ; -<4. 

globifera, 184/. 
Amphizonella, 80 
Ancyromonas, 165 
Anemineae, 55, 63 
Anisonema, 171 
Ankistrodesmus, 179 
Anopheles, 240 ; ^4. maculi- 

pennis, 248 
Antlwphysa, 158, 161, 167 ; 

-4. vegetans, 178 f. 
Apheiidinm, 3, 10, 11 ; ^4. 

lacerans, 11 
Aphrothoraca, 33 
Apiocystis, 180 
Apstein, 192 
Arachnula, 9 
.4rce/fo, 68, 71, 72, 85/., 86 

87, 90 ; A.vulffaris,90f. 
Arcellidae, 85, 90 
Archer, 22, 274, 277, 279 
Arcyria, 52 n., 55, 64, 65 ; 

.4. incarnata, 56 f. ; ^4. 

punicea, 56f. 
Arcyriaceae, 44, 55, 64 
Ascoglena, 157, 171 
Astasia, 171 ; .4. <eww^ 


Astasiina, 171 
Astrocapso, 146 ; A. coro- 

nata, 146; ^4. tritonis,I46 
* 1 strodiscv his, 33; .4 . 

radians, 16 /. 
Astrolophidae, 145 
Astrolophus, 145 
Astrosestrum acanthastrum, 


! Atliene noctua, 202, 233 
Athias, 254, 269 
Atlanticella, 109, 150; ^4. 

craspedota, 149 
Atractonema, 171 



Aulacantha, 113, 119, 121 ; 

Brass, 13 

Chactomorpha crassa, 10 

A. scolymantha, 111 /., 

Brauer, 31, 32, 35, 245 

Chalaro'thoraca, 23, 34 

112, 117, 121, 124, 

Braun, 13 

Challengeridae, 113, 148 

125 /., 136, 147 

Brefeldia, 63 

Challengeron armatum, 148 

Aulacanthidae, 147 

Breinl, 206 n. 

/. ; (J. balfouri, 148 ; C. 

A ulactin ium actinastrum, 

Bruce, 195, 199, 269 

golfense, 148 ; C. johan- 

109 /. 

Brumpt, 196, 198, 204, 

nis, 148 ; C. trioden, 

Aulodendron boreale, 148 

226, 228, 269 


A idographiftfurcellata, 148 ; 

de Bruyue, 4, 13 

Chilomonas, 176 

A. tetrancistm, 148 ; A. 

Buffard, 205, 269 

Chironomus plumosus, 245 

zetesios, 148 

Burstdla, 3> 11, 12, 40, 60 

Chlamydococcus, 180 

Aulokleptcs Jlosculus, 110, 

Biitschli, 5, 6 n., 13, 35, 

Clilamydomonadina, 180 

135 /. 

39, 66, 70, 91, 115, 131, 

Chlamydomonas, 22, 180 ; 

Auloscena vertidUatus, 112 

151, 190 

C. pulvisculus, 166/. 

/., 148 

Chlamydomyxa, 39, 274 ; 

A ulosphaera elegantissima, 

(J<H<iiii nii'fii, 148 

C. labyrinthuloides, 274, 

105 /. ; A.fiexuosa, 148 

Calcariueae, 49, 55, 62 

275 /., 279 /., 282 / ; 

Aulotractus fusidus, 148 

Calkins, G. N., 13, 20, 79, 

< '. Montana, 274, 277, 

Audcularia, 49 

91, 219 

278, 279 /. 

Awerinzew, 35, 91 

Calouemineae, 64 

Chlamydophora, 33 

Calymma, 95 

L'lilnrinJ.esmus, 158 

Badhamia, 52 n., 55, 62 ; 

Calyptrosphaera, 176 ; C. 

Chlorogonium, 180 ; C. 

B.panicea, 42/., 52 /. ; 

oblonga, 175/. 

I'uchlorum, 166 /. 

B. utricularis, 44 /., 46 

Campascus, 90 

Chloromonadina, 174 

/., 48, 49, 50/., 51 /. 

Camptonema, 33 

CJwanocystis, 35 

Barbagallo, B., 92 

Cannocapsa, 146 ; C. oscu- 

Choanortagellata, 176 

cle Bary, 38, 61, 66 

lata, 146 

Chodat, 22 

Basidiomycetes, 40 

Cannosphaera antarctica, 

Chodatella, 179 

Bathybius, 12 


Chondrioderma, 53, 54, 55, 

Belonaspidae, 146 

capillitium, 52, 55 

62 ; (7. testaceum, 54 f. 

Beneden, E. van, 2, 13 

Carpocanium diadema, 105 

Chondropus virulis, 33 

Berg, 195 

/, 147 

Christophers, 257, 272 

Bicosoeca, 161, 168 ; B. 

Carteria, 178, 180 

Chromatella, 80 

socialis, 158, 168 

Casagrandi, Q., 92 

Chromidia, in Heliozoa, 18 ; 

Bikoecina, 168 

Cash, J., 13, 78 

in Lobosa, 71 ; in Pro- 

Billet, 226, 269 

Castauellidae, 150 

teomyxa, 1 ; in Radio- 

Biomyxa, 2, 3, 9 ; B. cometa, 

Castanidium apsteini, 150 

laria, 121 

9 ; B. <cagans, 9 

Castellani, A., 92, 196, 

Chromomonadidea, 173 

Bionomics in Tlialassicolla, 


Chromulina, 157, 174; C. 



rosanojft, 173 

Blackmau, 180, 192 

Central capsule in Eadio- 

Chrysamoeba, 173, 174 

Blepharisma, 22 

laria, 114 

Ohrysococcus, 161, 174 

Blepharocysta, 186, 187 

Centralkorn, 28 

Chrysomonadina, 174 ; C. 

Boderia, 10 ; B. turneri, 

Centrochlamys, 80 

loricata, 174 ; C. mem- 

11 / 

Centropyxis, 71, 75, 76, 77, 

branata, 176 ; C. nuda, 

Bodo, 157,' 161, 162, 163, 

86, 87, 88, 89 


167, 246 ; B. caudatus, 

CepJuilothamnion, 161, 167 

Chrysopijxis, 174 

166 /. ; B. lacertae, 211, 

Ceratiidae, 187 

Cienkowski, on Chlamy- 

247; B. lens, 178/. 

Ceratiomyxa, 40, 57, 59, 

-. domyxa, 280 ; on Helio- 

Bodonina, 167 

64, 66 ; C. mucida, 58 f. 

zoa, 29, 35 ; on Labyrin- 

Borgert, 110, 119, 124, 

Ceratiomyxaceae, 64 

thula, 283 ; on Mastigo- 


Ceratium, 158, 186, 187 ; 

phora, 190 ; on Myceto- 

Botryocampe inflata, 147 

C. hirundinella, 183 n. ; 

zoa, 38, 43, 61, 66 ; on 

Botryococcus, 179 

C. tripos, 186 /. 

Protozoa, 4, 10 /., 13 ; 

Botryoidea, 147 

Ceratocorys horrida, 184/., 

on Racliolaria, 97, 152 

Bott, 91 


Cienkmvskia, Heliozoa, 34 ; 

Bourne, 81, 91 

Oercobodo, 166 ; C. crassi- 

Mycetozoa, 62 

Box boops, 247 

cauda, 166/. 

Ciliophrys, 4, 8, 10 /. ; C. 

Bradford, 206 n., 269 

Cercomonas, 165 

infusionum, 10 f. 

Brandt, 96, 97, 104, 106, 

Ccrelasma, 286 

Cimex rotundatus, 259 

110, 112, 127, 129, 152 

Certes, 273 

Circoporidae, 150 



Circoporus sexfuscin i's, 

112, 117 

Cistidium inenne, 105 /. 
Cladomonas, 168 
Cladophora, 11 
( 'li<l * I*-,: ,i iuin tricolpium, 

Cladothrix, 72 f. ; (7. ^>eZo- 

myxae, 81 
Classification of Haemofla- 

gellates, 248 ; of Helio- 

zoa, 33 ; of Lobosa, 

Gymnamoebida, 77 ; 

Thecamoebida, 84 ; of 

Mastigophora, 154 ; of 

Myceto/.oa, 61 ; of Pro- 

tuoniyxa, 6 ; of Radio- 

laria, 144 ; of Xenophyo- 

phoridae, 286 
Clastoderma, 63 
Clathrocydas craapedota, 

Clathrulina, 25, 29, 34 ; 

C. elegans, 16/., 23 
Closterium, 32 
Clypevlina, 90 
Coccolithoplioriuae, 176 
Coccolithqpora, 176 ; C'. 

lejttopora, 175 f. 
coccolitlis, 174 
Cocliliopodiidae, 84, 85, 88 
Cochliopodium, 71, 80, 88 ; 

C. actinophorum, 88 ; 

C. diijitntuni, 88 ; C. 

pellucidum, S8/. 
Cochlodinium, 185 
Codonoeca, 167 
Codosiga, 177 ; C. um- 

bel la ta, 178/. 
Coelodeudridae, 150 
Cododendron ramosissi- 

mum, 150 ; C. gracilli- 

minn, 105 /. 
Coelographidae, 150 
Coelomoiuts, 174 

murrayanum , 
151 /. : ''. trtkmit, 151 
Coelothamn us davidoffi, 
151 /. 

Coenobia, 181 
Colacium, 171 
Coleochaeta, 11 
Collodaria, 113 
<'i>l/,,ilict)/on, 169 
Collosphaera, 111 w., 121, 

12:; ; <_'. )iii.r/,-i/i, 140/. ; 

C. murrayaitc, 145 
Collospbaeridae, 104, 145 
Collozoum, 98, 139 /. ; C. 

fill rum, 138; C. inenne, 

103 /., 126 /., 138, 

141/., 142 /., 145; C. 
.pelagicum, 145 ; C'. 

radiosum, 138 
Colpodella, 3, 5, 10, 11 ; 

(7. pugnax, 10/. 
Colponema, 168 
columella, 53 
Comatricha, 52 n. , 55, 


Concharidae, 150 
Contractile vacuoles in 

Heliozoa, 18 ; in Lobosa, 

85; in Mastigophora, 

160 ; iu Mycetozoa, 49 ; 

in Proteomyxa, 3 ; in 

Radiolaria, absent in 

Thalassicolla, 97 
Convoluta, 22 ; O. ros- 

co/ensis, 129, 180 
Copromonas, 160 /., 161. 

162, 163, 171, 172, 177 ; 

C. subtilis, 172 
Copromyxa, 65 ; C. protect, 

60 /. 

Cornutella dathrata, 147 
Cornuvia, 64 
Cortina typus, 107 /. 
Cwtiniscus typicus, 146 
Corycia, 80, 89 
Costia, 157, 168 ; C. 

necatrix, 169 
Craig, C. F., 92 
Craspedomonadiua, 177 ; C. 

loricata, 177 
Craspedotdla, 190 
Craterium, 44, 54, 55, 62 ; 

C. pedunculatum, 54 /. 
Crawley, 23, 35 
(.'rilimria, 54, 63 
L'rithidiu, 228, 240, 241 /. ; 

C. campamdata, 245 ; 

C. fasciculate, 242, 248 
Gryptoglena, 171 
Cryptoruonadina, 176 
('-in nbalus kochii, 249 
Cucurbitdla, 89 

I'ipiens, 202 f., 233, 


Cyathomonas, 176 
Cydonexis annularis, 158 
Oycloptems lumpus, 247 
Cylindyospermum, 11 
Cyphoderia, 90 
Cyrtocalpis obliqva, 147 
Cyrtoidea, 114, 147 
Cystoflagellata, 188 
Cytodadus spinosus, 115 

/, 1*4 

, 179 
Dactylosjthaera, 79 ; /). 

polypodies 72 /., 73 ; 
/>. radiosa, 78/., 79 

l)n in <> ida reevesii, 254 
Bangeard, P. A., 3, 13 
Danilewsky, 195, 255, 269 
Delage, 39 
Delap, 153 
Dendromonas, 158 
Desmothoraca, 23, 25, 34 
Diachaea, 62 ; X>. elegans, 


Dianema, 64 
Diaphorodon, 90 
Diatoms, 11 
Dictydiaethalium, 63 
Dictydium, 54, 63 ; Z>. 

umbil ica him, 55 /. 
Dictyocephahis ocellatvs, 


Dictyomyxa, 10 
Dictyophimus clevei, 147 
Didyopodium, 127 
Dictyosteliaceae, 60, 65 
Bictyostdium, 60, 65 
Dictyota, 114 
Didymiaceae, 56, 62 
Didymium, 44, 55, 56, 62 ; 

Z). di/orme, 43 /. ; Z>. 

effusuflf, 57 /. 
Difflugia, 71 /, 72, 84, 

85, 86, 89 ; I>. globosa, 

86; D. pyriformis, 89 /. ; 

Z). urceolata, 86, 87, 88 
Difflugiidae, 89 
Dimastigamoeba, 165 
Dimorpha, 164, 165 
Dinamoeba, 68, 80 
Dinema, 171 
Dinobryon, 157, 158, 161, 

173, 174 ; Z>. sertularia, 

1-65 /. 

Dinoflagellata, 182 
Dinophysidae, 187 
Diiiophysis, 187 
Diplocouidae, 146 
Diploconus, 146 
Diplomita, 168 
Diplophrys, 283 ; Z). 

Archeri, 283 ; Z. ster- 

corea, 283 . 
Diplophysalis, 4, 5, 8 
Diplosiga, 177 
Discoidea, 145 
Discorbina, 112 
DiscospJiaera, 176 ; Z>. 

tabifer, 175 f. 
Distephanits speculum, 191 
Distigma, 171 
Distomatina, 169 
Dobell, 160 ., 163, 172, 





Doflein, F., 13 

"Fingersand Toes" disease, 

Gymnosphaera, 23. 33 

Donovan, 256, 272 


Gyromonas, 169 

Dopter, 82, 92 

Flagellata (Mastigophora), 

Dorataspidae, 146 


Hacker, 113, 117, 122, 153 

Dorataspis, 127 

flagellulae, 4, 5, 29 

Haeckel, 1, 13, 104, 110, 

Dourine, 196, 197, 206 

Flowers of Tan, 47 

119, 127, 131, 152, 284 

Dreyer, 116, 131, 152 

Forde, 196 

Ilaeckelina, 8 

Dum-dum fever, 256 

Fowler, 113, 152 

Haematococcus, 180 ; //. 

Durham, H., 240 

Franya, 254, 269 

palustris, 166 f. 

Dutton, 196, 255, 269 

Freuzel, 91 

Haemaiomonas, 250 

Frenzdina, 90 

Haematopinus, 198, 203 

Echinomma leptodermum, 

Fuligo, 50, 55, 56, 57, 62, 

Haematopota. 242, 258 


65 ; F. septica, 40 /., 

Haemoflagellates, 193 ; bio- 

Echinostelium, 63 

47, 57 /. 

logical considerations, 

Ectobiella, 3/., 12 

217 ; classification, 248 ; 

Ehrenberg, 17, 112, 151, 

comparative morphology, 


Gamble, 22, 35, 99, 110, 

207 ; evolution ami 

Eikenia, 80 

129, 153, 180, 192 

phylogeuy, 240 ; habitat, 

Elaeorhanis, 14, 22, 23, 34 

Gametocytes, 25 

196 ; historical, 194 ; 

Elaster, 35 

Gasteromycetes, 40 

Leishman - Donovan - 

Elpatiewsky, W., 93 n. 

Gazdletta, 149 

Wright bodies, 255 : life- 

Enchylema, 69 

Geddes, 274, 280 

cycle, 226 ; list of hosts, 

Endamoeba, 68, 71, 82 ; 

Giemsa, 196 

162 ; literature, 268 ; 

E. blattae, 74 /., 83, 

Glaeocystis, 180 

multiplication, 222 

84 /. ; E. coli, 73, 74, 

Glenodiniidae, 186 

Halistemm a tergestin u m , 

75, 82 /. ; E. histolytica, 

Glenodinium cinctum, 184 


75, 82, 83/. ; E. iurai, 

/. ; G. pulvisculus, 187 

Halteridimn, 236, 248 

83 ; E. undulans, 83 

Gloidium, 2, 3, 5, 6/. 

Hanburies, 3 

Endosporeae, 40, 57 

Glossina, 200 ; G. fusca, 

Hauna, 270 

Endyonema, 2, 3, 5, 12 

199 n., 200, 201; G. 

Haplococcus, 3, 12 

Enerthenema, 62 

morsitans, 199; G.patti- 

Harper, 65 

Engler, 191 

dipes, 199 n. ; G. pal- 

Hartmaun, 159 ., 192 

Enteridium, 63 

palis, 199, 200, 231 ; G. 

Hartog, E., 13, 68 

Enteromyxa, 3, 12 

tachiiioides, 200 

Hedriocystis, 23. 34 

Entocanmda hirsuta, 148 

Gluge, 195 

Hdcosoma tropicum, 259 

Entosiphon, 171 

Goebel, 13 

Heleopera, 85, 90 

Esox lucius, 255 

Goes, 284, 286 

Heliophrys, 33 

Estrdla, 33 

Goldschmidt, R., 91, 163, 

Hdiosphaera inermis,103f. 

EucecrypJialus, 128 

164, 192 

Heliozoa, 14 ; classification, 

Eucoronis nephrospyris, 146 

GolenJdnia, 33, 179 

33 ; food, 18 ; karyo- 

Eucyrtidium, 127 ; E. 

Gomphonema, 7 

kinesis, 25 ; literature, 

cranioides, 108 f. 

Gonium, 158, 182 ; G. 

35 ; nucleus, 25 ; re- 

Eudorina, 181, 182 

pectorale, 158, 166 /. 

production, 28 ; skeletal 

Euglena, 157, 161, 171 ; 

Gonyaulax, 187 

investments, 23 ; struc- 

E. acus, 166 /. ; E, 

Grassia, 164 

ture, 15 

gracilis, 172 ; E. mridis, 

Gray, 199, 200, 203, 230, 

Hemiclepsis. 227 

166/., 172 


Hemidinium, 183, 184 

Englenina, 171 

Greeff, 22, 24 

Hemitrichia, 55, 64 ; H. 

Euglenoidea, 170 

Greenwood, 49, 66 

chrysospora, 56 f. 

Euglenopsis, 171 

Greig, 199 

Herouard, 39 

Eu-mycetozoa, 39 

Grenadier, 23, 28, 35 

Herpetomonas, 157, 161, 

Euplasmodida, 39, 40, 43 

Gruber, 78 

226, 240, 241, 250 ; //. 

Euphysetta natlwrsti, 148 

Gruby, 269 

biitschlii, 245 n. ; 11. 

Eutreptia, 171 

Gubernaculum, 159, 194 

bombycis, 245 ; H. culicif, 

Evans, G., 195 

Quttulina, 60, 65 

242 ; H. gracilis, 241,- 

Exoeporeae, 40, 57, 64 

Guttuliuaceae, 65 

245 ; //. jaculum, 241 ; 

Exuviaella, 185 ; E. 

Gynmamoebida, 77 

H. lewisi, 195 ; //. 

marina, 127 

Gymnococcus, 3, 5, 11 

minuta, 241 ; H. mnscae- 

jSfymnodinium, 183, 184 

domesticae, 232, 241 ; 

Famintzin, 58, 66, 98, 129, 

Gymnophrys, 2, 3, 9 ; G. 

H. sarcophagae, 245 ; H. 


cometa, 10/. 

subulate, 241 /. 



Hertwig, on Heliozoa, 15, 

Jalin, 42, 65, 66 

Lebailly, 270 

24 /., 25, 27, 31, 32, 

James, 272 

Lecquereusia, 89 ; L. 

35 ; on Lobosa, 75, 87, 

Jenkinson, 280 

spiralis, 89 /. 

91 ; on Radiolaria, 114, 

Jennings, 70, 91 

Leeuwenhoek, 155 

115, 123, 127, 152 

Johnstone, 129, 153 

Leger, 196, 198, 215, 

Heterodevmaeeae, 63 

Jiirgeiis, 92 

217 n., 226, 229, 230, 

', 187 

234, 240, 242, 245, 247, 

Heteromastigina, 248 

Kala-Azar, 256 

257 ., 258, 270, 271 

Heteromastigoda, 167 

Karawiew, 123, 152 

Leidy, 23 

heteromastigote, 158 

Karyokinesis, in Actino- 

Leishman, 196, 257, 272 

Heterophrys, 21, 22, 28, 

sphaerium,25 ; in Lobosa, 

Leishmania donovani, 232, 

34, 16-t ; //. Fockei, 24 

73 ; in Mastigophora, 

256, 257 f. ; L. tropica, 

/. ; //. myriopwia, 16/., 

161 (Noctiluca, 190) ; 

257 f., 259 


in Mycetozoa, 46/., 48. 

Leishman- Donovan- Wright 

Hexacon t ium entha can- 

65 ; in Proteomyxa, 2 ; 

bodies, 255 

tli in in, 145; //. pachy- 

in Radiolaria, 126 ; in a 

Leocarjivs, 62 

derm itm, 145 

Trvpanosome, 213 

Lcpidoderma, 56, 62 ; L. 

Hexacoiixs, 146 

Keeble, 22, 35, 99, 110, 

tigrinmim, 54 f. 

Hexadon's ICH-CHU*. 145 

129, 153, 180, 192 

Lepocindis, 171 

Hexalaspidae, 146 

Kempner, 198, 272 

Leptodiscns, 190 

Hexalonche philosophical,- 

Kent, 195 

Leptomonas, 165 


Ken ten, 172 

Leptophrys, 2, 3, 4 /"., 5, 8 

ins, 157, 162, 169 ; 

Keysselitz, 198, 229, 270 

Lesage, 82, 92 

//. !,(ftatus, 178 /. ; H. 

Klebahn, 35 

Lesser, 15, 24 /. 

muris, 170 

Klebs, 127, 153, 161, 165, 

Lethodiscus microporus, 

Hexaplagia arctica, 147 



Hickson, 162, 192, 194 n. 

Koch, 200, 203, 251 n., 

Lenciscus erythvoplithal- 

Hieronymns, 274, 276, 280 


mxs, 249 

Hinde, 153 

Kofoid, 182, 187, 192 

Lewis, 195 

liip-paraplegia, 206 

Kranzlin, 65 

Ley den, 91 

Hippobosca rufipes, 1 99 /. 

Krohn, 188 n. 

Leydenia, 84 ; L. gemmi- 

Hirmidium, 158, 177 

Krukenberg, 50, 66 

para, 84 

Histioneis, 188 ; //. cym- 

Krzysztalowicz, 273 

/./''//, 63 ; /.. i>nxilla, 56 

bcdaria, 184/. 

Liceaceae, 63 

Hoffmann, 273 

Labyrinthula, 39, 276, 

Lieberkiihn, 84 

Holmes, '206 n. 

280 ; L. cienkn:<l.-ii, 

Life-history of Chlamy- 

Holomastigoda, 164 

280 ; L. macrocystis, 

domyxa, 274 ; of Haemo- 

holomastigote, 158 

'- 280, 282/. ; L. vilellina, 

flagellates, 226 ; of Helio- 

IliJn/i~tii;nm((, 286 

129, 280, 282 /. 

zoa, 15 ; of Lobosa, 75 ; 

Homokaryota, 68 

Labyrintlmleae, 39 

of Mastigophora, 155, 

Hoogenraad, 13 

Lachnobohts, 64 

162, 164, 172, 180, 189; 

Hosts of Haemoflagellates, 

Lamblia intestinodis, 170 

of Mycetozoa, 40, 58, 

list of, 262-268 

I.iiiii/io.rniit!ui/iii ninrmy- 

."'.i ; of Proteomyxa, 3 ; 

Huxley, 151 

anum, 144 

of Radiolaria, 104, 111 

Hycdobryon, 157, 158, 174 

Lamproderma, 62 

Lignii-res, 218 n., 219, 271 

Hyalodiscns, 80 

Lamprosporales, 63 

lime-knots, 55 

lhi<ti<,li<,fl]if. 34 

Lang, A., 13 

Liit/Hi/fii/i/i, 63 

IIi/il,unn, 40 

Lankester, on Chlamy- 

Lingard, 271 

lliiilriii-l'ni'rn* capybara, 

domyxa, 274, 277, 280 ; 

Linf/lij/a, 2, 8 


onHaemoflagellates, 195, 

liniii, 18 

Hydrodictyon, 179 

270 ; on Heliozoa. 17, 

Lister, A., 61, 67 

Hydrnrna, 176 

36; on Ijiliirintlmla., 

Literature, of Chlamydo- 

'inonas, 161, 176 

283 ; on Lobosa, 80 ; 

'inii-i'ii, 279 ; of Hsemofla- 

hypnocysts, 4 

on Mastigophora, 158 .,' 

gellates, 268 ; of Heliozoa, 

liypothallus, 54 

162, 168 H. : on .Myce- 

35 ; of La bi/riji tl nln. 

tozoa, 67 ; pu Radiolaria, 

' 283 ; of Lobosa, 91 ; of 

Ji/iiii-Ju-ii/in'tlt'c., 71 


Mastigophora, 191 ; of 

Ijima, 91 

Larcoidea, 145 

Mycetozoa, 66 ; of Pro- 

Immermaun, 110, 153 

Laveran, 196, 204, 206 7?., 

teomyxa, 13 ; of Radio- 

Ineffigiata, 179 

207, 218 n., 245. 252, 

laria, 151 ; ofXenophyo- 

isomastigote, 158 

268, 270, 272, 273 

jilioridae, 286 



Lithamoeba, 80 ; L. discus, 

Mikroyromia, 39, 281 

18 ; iu Actinosphaerium, 

80 /. 

Miuchin, 159 n., 192, 196, 

25,32; in Labyrin tlmln, 

Lithelius arborescens, 145 ; 

199, 200, 201, 203 n., 

280 ; in Lobosa, 70, 86 ; 

L. minor, 145 

230, 231, 233, 246, 271 

in Mastigophora, 161 ; in 

Lithocircus annular is, 105 

Mitrophauow, 195, 271 

Mycetozoa, 48, 59 ; in 

/., 146 

Monadiua, 38, 248 

Proteomyxa, 2 ; in Radio- 

Lithocolla, 34 

Monadineae, 5, 6 n. 

laria, 94, 107, 110, 120 

Lithogromia silicea, 148 

Monadopsis, 8 

Litholophus, 111 

Monas, 166, 167 

Oat-shaped corpuscles, 39, 

Lithomelissa setosa, 147 ; 

Monera, 1 


L. thoracites, 147 

Monobia, 3, 5/., 6, 15 

Ochromonas, 157, 174 

Litlwspluierella, 34 

Monocercomonas, 169 

Oedogonium, 8 

Lobosa, 68 ; ehromidia, 71 ; 

Monolabis, 22 

Oicomonas, 157, 165 ; 0. 

classification, 77 ; litera- 

Monomastigoda, 165 

mutabilis, 166 /. ; 0. 

ture, 91 ; nucleus, 70 ; 

Monomastigote, 158 

termo, 166/. 

reproduction, 72 

Monomastix, 159, 170 

Oligonema, 64 

Lohmami, 174, 192 

Monophyes gracilis, 249 

Olive, 60, 66, 67 

Lophomonadina, 170 

Monopodittm, 8 

Oread el la, 63 

Lophomonas blattarum, 

Monopylaria, 103, 107 

Ornithocercus, 186, 187 ; 

178 /. 

Monostomatina, 169 

0. magnificus, 184 f. 

Lotsy, 192 

Monticelli, 13 

Orosphaera, 122, 144 

Liihe, 245, 247, 268 

Moore, 159 n., 192, 206 n. 

Orosphaeridae, 144 

Lycogala, 56, 64 

Mucorinae, 40 

Ostenfeld, 36 

Lycogalaceae, 64 

Mugliston, T. C., 93 

Ouramoeba, 78/., 79 

Miiller, Johannes, 131, 151 

Oxyrrhis, 163 n., 168, 

Mallomonas, 161, 176 

Multicilia, 160, 163, 164; 


Margarita, 64 

M. lacustris, 164 

Oxytoxum, 187 

Margaritaceae, 64 

Murray, J., 13, 113, 192 

Martini, 91 

Murrayella, 187 

Palmella, 180 

Mastigamoeba, 160, 164; 

Musgrave, W. E., 93 

Palmella stage in Zoo- 

M. schulzei, 164 

Mycetozoa, 37 ; classifica- 

xanthellae, 98 ; in Flagel- 

Mastigella, 156, 163, 164, 

tion, 61 ; life-cycle, 42 ; 

lates, 156 

177 ; M. i-itraea,159f., 

literature, 66 

Palmodactylon, 180 

164 /. ; M. vitrina, 164 

Myxastrum, 3, 5, 8 

Palmodictyon , 180 

Mastigina, 160, 164 ; M. 

Myxodictyum, 11 

Pandorina, 182 

setosa, 164 

Myxodiscus crystalligerus, 

Pantostomatiua, 164 

Mastigophora, 11, 155 ; 


Paramastigoda, 167 

classification, 163 ; habit, 

Myxosphaera coerulea, 140 

paraniastigote, 158 

157 ; literature, 191 ; 

Pi'.miiieciiiiit, 20 ; P. cos- 

nucleus, 161 ; nutrition, 

Nabarro, 199, 252 

tatum, 195 ; P. lorica- 

157 ; structure, 158 

Nadinella, 90 

tum, 195 

Maupas, 20 

Nagana, 195, 197, 198 

Paramoeba, 79; P. eUhardi, 

Maupasia, 159, 170 

Nassellaria, 107, 113, 114 

70 /., 73, 75, 79, 83; 

Mayer, 195 

Nationaletta, 149 

P. hominis, 79, 83 

M'Neal, 217, 218 n., 223, 

Nawaschiu, 11, 13 

Paramoecoides, 250 

227, 240, 242, 244, 245, 

Nebela, 85, 87, 90 

Paranema, 171 ; /'. trlcho- 

253, 271 

nebenkorper, 70 

phorum, 166/. 

Medusetta tiara, 148 

Nepveu, 196 

Paranemina, 171 

Medusettidae, 148 

Neresheimer, 71, 91 

Parmulina, 89 

Megastoma, 157, 169; M. 

Neusina agassizii, 284 

Patton, 242, 259, 271, 273 

entericum, 169 

Noctiluca, 162, 188, 190 ; 

Pediastrum, 179 

Menoidium, 171 

N, miliaris, 161 /., 189 

Pelomyxa, 2, 68, 70/., 71, 

Mereschkowsky, 13 

/., 190 /., 191 /. 

73, 75, 76 /., si ; P. 

Mesenteries, 44 

Novy, 200 n., 217, 218 n., 

palustris, 72 /., 76 ./'., 

Mesnil, 91, 196, 204, 206, 

227, 239, 240, 242, 244, 

81 /. ; P. penanU. 81 ; 

207, 218 n., 245, 252, 

245, 253, 271 

P.villosa,Bl; I', viridis. 

272, 273 

Nudearia, 8, 9, 14, 15, 23, 


Mesoscena, 114 

33 ; N. ddicntula, 10/. 

Penard, E., 13, 22, 23, 33, 

Metschnikoff, 50, 67 

Nuclei in Chlanu/domyxn, 

36, 39, 67, 91, 274, 277, 

microcysts, 42 

274 ; in Haemotta^ellates, 

278, 280 

Microglena, 161, 176 

194, 212 ; in Heliozoa, 

Penardia, 3, 9 



Perichaena, 64 

Plate, 190 

Protogenes, 5, 9 ; P. jtriin- 

Peridiniaceae, 185 

Platnaspis, 146 

ordialis, 9/. 

Prridinium, 186 187 ; P. 

Platoion, 90 

Protomastigiua, 165 

dicergens, 186 /. 

Platydorina, 158, 182 ; P. 

Protomonas, 11, 60 ; P. 

Peripylaria, 102 

caudata, 182/. 

amyli, 38 ; P.paroaitii-n, 

Perrin, 273 

Platytheca, 167 


Petalomonas, 171 

Plectellaria, 147 

Protomyza, 3, 4, 7/1, 11 ; 

Pliaeoconchia, 150 

Plectoidea, 147 

P. parasitica, 10 /. 

Phaeocy.stina, 147 

Plectophora arachnoides, 

Prototrichia, 64 

Phaeodaria, 108, 113 

147 ; P. novena, 147 

von Prowazek, on Haemo- 

Phaeogromia, 148 

Plehn, 271 

flagellates, 198, 205,212, 

Phaeosphaera, 176 

Plenge, 42, 67 

223, 229, 231 M., 232, 

Pliaeosphaeria, 148 

Pleodorina, 181, 182 ; P. 

257 71., 271 ; on Helio- 

Phalaeroma, 188 

illinoisensis, 183 f. 

zoa, 35 ; on Mastigo- 

Phalansteriina, 177 

Pleurococcus, 179 

phora, 159 H., 163, 192 ; 

Barium, 158, 163.. 

Pleuromonas, 167 

on Proteomyxa, 4 w. 

177 ; P. consociatum, 166 

Plimmer, 206 ?i., 269 

Prunocai-pi's d'.<tn,-a, 145 

/. ; P. volvocis, 168 

Podolampas, 187 

Pmnoidea, 145 

Pkarynyella gastrula, 148 

Polykrikos, 185 

Prunophracta, 146 

Plwrmobotrys hexathalom iu, 

Polymastigiiia, 169 

Psammeftn, 286 


polymastigote, 158 

/'^rt?;! ; //ia gldbigerina, 

Phorl iciu m pylon in m, 145 

Polyoeca, 177 


Phractopeltidae, 146 

Polyplagia novenuria, 147 

Psammini<Ii/c, 286 

Phryganella, 90 

Polyporus, 40 

Psamr/uijie/nmii, 286 

Phyllomitus, 167 

Polysphondylium, 60, 65 ; 

Pseudamphimonas, 11, 12 

Phyllomonas, 167 

A violaceum, 60/. 

Pseudochlamys, 89 

Phyllostaurus, 146 ; P. 

Polytoma, 177 ; P. nvella, 

Pseudodijfluyia, 90 

<[U<n! rifolius, 146 


Pseudopodia, of Heliozoa, 

Physaraceae, 56, 62 

Pompholyxophrys, 22, 24, 

23 ; of Lobosa, 85 ; of 

Physarella, 62 


Mastigophora, 160 ; of 

Physarum, 52 ?;., 55, 62 ; 

Pontigutasia,89 ; P. incisa, 

Proteomyxa, 3; of Radio- 

P. mutans, 54 f. 


laria, 96, 106 

Physematiidae, 104, 144 

Pontobdella, 204, 224, 

Pseudospora, 3, 5, 8, 163 

Physematium, 121 ; P. 


Pseudosi><>ri<?him, 10, 12 

niiiUcri, 144 

Pontomyxa, 9 ; P. Jtaca, 

Ptychodisfidao, 187 

J'hysomonas, 167 

9 ; P. pcdlida, 9 

PtycKo&iscus nocticula, 187 

Phytheliii-ft, 33 

Pontosphaera, 176 ; /'. 

pulsellum, 158 H. 

PhytoHagellata, 177 

haeckelii, 175/. 

Putter, 98, 153 

P inaciophora, 24, 34 

Popowsky, 136, 153 

''H/H'iias (=J'yra- 

Pinacocystis, 21, 24, 34 

Porocapsa, 146 ; P. wittr- 

mimonas), 179, 180 

Piroplasma, 256 ; P. <2ouo- 

rayana, 146 

Pi/riil>}ui,-nx l 187 

Ewnt, 243, 257 /., 259 

Poroapathidae, 148 

/'// > iilicuia, 91 

Playiacantka arachnoides, 

Poteat, \V., 91 


Poteriodendron, 158, 161, 

Quadrula, 84, 85, 89 ; <,>. 

Plagiocarpa procyrtella, 


'/ulin'is, 84 


Pouchetia. 185 

Quatrefages, 189 

Plagoniscus tripodiscus, 

I'm, if I, 192 


Pricolo, 171 

Rabinowitscli, 198, 272 

Planktonetta attantica, 

Proales, 23 

Radiolaria, 94 ; bionomics, 

120/., 149 /. 

Prorocentraceae, 185 

96 ; central capsule, 114 ; 

Plasmodiocarps, 56 

Protamoeba, 2, 5, 6 

classification, 144 ; cyto- 

Plasmodiopfwra, 2, 3, 4 ., 

Proteomyxa, 1 

plasm, 116 ; distribution, 

5, 11 

I'roterosponyia, 158, 177 ; 

112; food, 97; literatim-, 

Plasmodium, in Labyrin- 

P. haeckelii, 178 f. 

151 ; nucleus, 120 ; repro- 

fh/'/fi, 282 ; in Lobosa, 

I*r/>tn!Kithybiiis, 12 

duction, 136 ; skeleton, 

72 ; in Mycetozoa, 43, 

Protocerativ.m, 187 

130 ; variation in, 110 ; 

57 ; in Proteomyxa,3 

Protococctis, 180 

yellow cells, 126 

plasson, 2 

Protocystis harstoni, 148 ; 

Raphi'l.iiiiK'iitix, 174 

plastogamic fusion, in 

P. tridens, 148 ; P. <ri- 

Reinak, 195 

Heliozoa, 19; in Lobosa, 

/o/(/x. 148 ; P.xiphmhn, 

Reproduction, in Chlamy- 



domyxa, 275 ; in Hae- 



moflagellates, 222 ; in 

Schneider, 5/., 13, 31, 32, 

Stannoma, 284, 286 

Heliozoa, 19, 28 ; in 

205, 269 

Stanuoniitla, 286 

Lobosa, 72 ; in Masti- 

Schroder, 122, 153 

StannophyUum, 284, 286 ; 

gophora, 156 ; in My- 

Sclmberg, A., 92 

S. zonarium, 284 f. 

cetozoa, 41 ; in Proteo- 

Schubotz, 92 

Statham, 257, 272 

myxa, 4 ; in Racliolaria, 

Schultze, 285, 286 

Steel, 195 

99, 136 

Schiitt, 187, 192 

Stegomyia, 240 

Reticularia, 52 n., 56, 64 ; 

Sclerotiuin, 44, 50 

Steiniella, 187 

R. lycoperdon, 42/. 

Scyphosphaem, 176 ; S. 

Stemonitaceae, 53, 62 

Reticulariaceae, 63 

apsteini, 175./'. 

Stemonitis, 62 ; S. ferrii' 

rhabdoliths, 174 

Scytomonas, 171 

ginea, 55 /. ; S. fusca, 

Rhabdomonas, 171 

Selenastrnm, 179 

41 /., 57 ; S. splendens. 

Rkabdosphaera, 176 

Seim, 192, 212, 272 

55 f. 

Rlwphidiophrys, 22, 24, 

Sergcnt, 196, 226, 272 

Stephanosphaera, 158, 182 

28, 34 ; R. elegans, 35 /. ; 

Siedlecki, 273 

Stephoidea, 147 

R. pallida, 16 /. ; R. 

Siphonosphaera, 121, 123 

Stereum, 49 

viridis, 22, 23 

Siphoptychium, 63 

Sterromonas, 167 

Rlutpkidocystis, 24, 34 

Smith, 31, 36 

Stichogloea, 176 

Rhipidodeiidron, 158, 168 

Sorokin, 13 

Stole, A., 92 

Rhizomastigoda, 164 

Sorophora, 39, 59, 65 

Stomoxys calcitrans, 199 /. 

Rhizoplasma, 9 

Sphaerastmm, 28, 34 

Strasbnrger, 52 n., 67 

Rhizoplegma boreale, 145 

Sphaerella, 179, 180 ; S. 

Streptomonat, 168 

Rhunibler, 5, 6 n., 13, 70, 

jacdustris, 166/. 

Stuhlmann, 200, 203, 216, 

85, 91 

Sphaerellaria, 106, 113, 

230, 231, 272 

Rhynchomonas, 168 


Stylamoeba, 80 

Robertson, 163, 169, 192, 

Kphaerocapsa, 146 ; <S. 

Stylochrysalis, 157, 163 n., 

204, 214 n., 216 n., 224, 

c-niciata, 146 


228, 229, 272 

Sphaerocapsidae, 146 

Swingle, 225 n. , 272 

Rogers, 226, 257, 272, 273 

Sphaerocystis, 180 ; S. 

Symbiotic Algae (Peridin- 

Romanowsky, 196 

Schroteri, 22 

' ians), 94 

Roubaud, 203 n., 231 n. 

SpJiaeroeca, 158, 177 

Syncrypta, 173, 176 ; S, 

Ross, 240, 242, 272 

Sphaeroidea, 145 

voh-ox, 166/. 

Jiitppia, 3 

Sphaerophracta, 146 

Synura, 157/161, 176 

Sphaeropylidea, 145 

Syracoaphaera, 176 

Sphaerozoa, 102, 104, 145 

Syracosphaerinae, 176 

Sagena ternaria, 148 

Sphaerozoidac, 104, 145 

Migenoarium, 148 

Sphaerozoum neapolitanum, 

Sagospkaera trigonilla, 148 

138, 141/. ; S. ovodimare, 

Tabanus, 242 ; T. lineola, 

Sagosphaeridae, 148 


199 /. 

Salpingoecct, 161, 177; S. 

Spkenomonas, 171 

Tansley, 180, 192 

fusiformis, 178 /.; S. 

Spirilla, 195 

Tanypu-s, 245 

urceolata, 178/. 

Spirochaeta evansi, 195 

Tetramitus, 157, 169 ; T. 

Saltonella, 80 

Spirodinium, 183, 185 

rostratus, 178 f. ; T. sul* 

Saunders, 49 

Spirogyra, 7, 8, 32 

catus, 178 f. 

Schaudinn, on Haemofla- 

Spiroidea, 147 

Tetramyxa, 2, 3, 11 

gellates, 196, 198, 202, 

Spironema, 170 

Tetraspora, 180 

205, 212, 217, 226, 235, 

Spirula, 11 

Thalassicolla, 94, 113, 114, 

241 n. , 248 n., 258, 272, 

Spongodisms favus, 145 

123 ; T.pelagica, 95 /. j 

273 ; on Heliozoa, 27, 

Spongomonas, 168 

T. pellucida, 144; T. 

29, 32, 34, 36 ; on 

Spongosphaera streptacan- 

nitcleata, 98, 99, 101/., 

Lobosa, 70, 75, 87, 88, 

tha, 105/. 

103/., 144; T.spumida, 

92 ; on Mastigophora, 

Sporangia, 50 


163, 192; on Proteo- 

Spores in Mycetozoa, 53 ; 

Thalassicollidae, 104, 144 

myxa, 6 n. ; on Radio- 

in Proteomyxa, 4 

Th alassiosolen atlant icns, 

laria, 153 

Sporophore, 58 


Scheel, 74, 92 

Spumaria, 56, 57, 62 ; S. 

Thalassolampe, 121 ; T. 

Schewiakoff, 118, 131, 153 

alba, 54/. 

margarodes, 144 

Schizochlamys, 180 

Spumellaria, 113 

Thalassophysa, 120 ; T, 

Schizogenes, 12 

Staborgan, 188 

papillosa, 144 ; T. pel a* 

Schleiincysten, 232 

Stahl, 61, 67 

gica, 138 /., 144 ; T. 

Schleppgeissel, 194, 218 

Stannariiim, 286 

sanguinolenta, 128 f. , 



138 /., 144 ; T. ,^/<v- 

247, 249 ; 7 1 . iwrttaa, 

ii.rimn, 195 /., 254 ; T. 

losa, 138/. 


scyllii, 204, 255 /. ; T. 

Thalassophysidae, 104, 144 

Tn/j>anoscmia, 157, 163, 

soleae, 210 /., 217 ; T. 

Thalassothamnidae, 144 

168, 177, 248, 250 ; T. 

theileri, 199 /., 209, 

Thalassothamnus, 122 f. ; 

ai'iKM, 208/., 217, 253 ; 

251 n., 253 ; T. tmns- 

T. ramosus, 144 

T. ba-rbdtulae, 215, 227, 

vaaliense, 216, 253 ; T. 

Thecamoebida, 68, 84 

228, 230 ; T. boneti, 254 ; 

ugandense, 252 ; T. tai- 

Theoconus ariadnes, 147 

T. brucii, 195, 199 /., 

dulans, 255 ; T. mriuiii, 

Thiroux, 218 ., 239, 272 

200, 201, 203, 208 /., 

227 ; T. ziemanni, 205, 

Thread -plasmodium, 39, 

209, 214, 215, 216, 217, 

208 /., 233, 237 /., 238, 


220 /., 221 /., 223 /., 


Todd, 255 

231, 233 ; T. carassii, 

Trypaiiosomatidae, 248 

Topfer, 237 u. 

255 ; T. cobitis, 255 ; 

Trypanosomes, 193, 213 f. 

Topsent, 13 

T. costatum, 254 ; T. 

Trypanozoon, 248 

Torrey, 237 n. 

damoniae, 208 /., 254 ; 

Tsetse-fly, 196, 201 n. 

Ti-achelomonas, 161, 171 

T. danilewskyi, 204 ; T. 

Tubulina, 63 ; T. stipitata. 

tractellum, 158 n. 

dimorphon, 253 ; T. 


Trepomonas, 169 

duttoni, 205 ; T. elegans, 

Tubulinaceae, 63 

Trepospyris corliniscus, 

255 ; T. elmassiani, 253 ; 

Tulloch, 199, 200, 203, 

107 /. 

T. equinum, 197, 199/., 


Trichamphorn, 62 

205, 208 /., 217, 220 /., 

Tuscarora national is, 122 

Trichia, 52 n., 64 ; T. 

221 /., 224 /., 251 /., 

/., 150 /. 

fallax, 52 n., 53 ; T. 

253 ; T. equiperdum, 

Tuscaroridae, 150 

varia, 53/., 56 / 

197 n., 205 /., 209, 

Tiiscarvsa globosa, 150/. 

Trichiaceae, 44, 55, 64 

224 /., 251 /., 253; T. 

Trichoinastix, 157, 169 

evansi, 199 /., 253 ; T. 

Trichomonas, 157, 160, 

flesi, 255 ; T. gambiense, 

Ulothri.c, 156 

162,169 ; T. intestutoltg. 

196, 197 n., 199, 200, 

Ulotrichaceae, 156 


203, 208 /., 220 /., 221 

Umbilicosphaera, 176 

Trichosphaerium, 22, 68, 

/., 230, 251 /., 252; T. 

Undwliiia, 250 

72, 73, 75, 80, 102, 127 

granulosum, 204, 209, 

Urceolus, 171 

Ti-i'J/'i.-tyopus, 115 ; T. efe- 

210 /., 228, 255; T. 

Uroglena, 158, 173, 176 ; 

<?, 147 

grayi, 200 n., 201, 215, 

U. ranarum, 106 /., 194 

Trigonomonas, 169 

216/..224/., 231, 232/., 

/., 195, 254 ; U. wlvox, 

Trimastigina, 169 

233, 245, 246, 251 ; T. 


Trimastix, 169 

liannae, 208/., 209, 216, 

Urophagii-s, 169 

Triposolema, 188 

253, 254 ; T. inopina- 

Tripylaria, 102, 108. 147 

fi'ni, 210 /., 216, 255 ; 

Trochiscia, 179 

T. johnstoni, 214 ., 

Vacuolaria, 174 

Trochodiscus ech in /*//..,, 

253 /., 254 ; T. karyo- 

Vahlkampf, 70, 92 

145 ; T 7 . heliodes, 145 

zeukton, 210 /., 212, 

Valentin, 194 

Trophochromidia, 71 

255 ; T. lewisi, 197, 198, 

Vampyrdla, 2, 3, 4/., 5, 

Trophonucleus, 214 

203, 204, 205, 207 /., 

7/., 15, 33 

Tropidoscyphus, 171 

208 /., 210, 211 f., 214, 

Vampyrellidium, 2, 3, 8 

TruncatidincT, 112 

216, 217, 219 /., 222, 

Veley, 71, 81, 92 

Trypanomonas, 250 

225 /., 226 /., 229, 

Vernon, 98, 152 

"Hiorpfia, 167, 198, 

251 n., 252 ; T. mega, 

Verworn, 13, 95, 152 

238, 248 

212, 255; T. nanum, 

Voges, 272 

Trypanomorphidae, 167, 

209 ; T. ndspruitense, 

Volvociua, 181 


210 /., 255 ; T. noctuae, 

Volvox, 158, 181 ; V. 

Trypanqphis, 168, 209, 

198, 202, 205, 208 /., 

aureus, 182 ; V. globator, 

211, 213, 216, 249; 7 1 . 

213, 218, 219 /., 223, 

166 /., 181 ; V. minor, 

grobbeni, 211, 249 /., 

233, 242, 243, 247, 248 ; 

166/. ; V. tertius, 182 


T. paddae, 253 ; T. 

Trypanoplasma, 168, 209, 

polyflectri, 209 ; T. raiae, 

211, 217,249; T.borreli, 

204, 209, 216, 224, 228, 

Wagnerdla, 34 

210 /., 211, 215 /., 216, 

231, 255 /. ; T. remaki, 

Wasielewsky, 212. 272 

217, 249; T. cjjprini, 

204, 209, 210 /., 216 ; 

Watase, 189 

210 /., 211, 249 ; T 7 . 

T. rotatorium, 208, 209, 

Weuyon, 192 

intestincdis, 247, 249, 

210 /., 216, 248 ., 

West, G. S., 13, 36, 

250 /. ; T. rentriculi, 

250 n., 254 ; T. sangulnis 



Wolfenden, 113, 152 
Woodcock, 193 n., 268 
Woronin, 3, 13, 58, 66, 

173, 192 
Wright, S., 13, 256, 273 

Xanthellae, 22 


Xiphicantha (date, 128, 
142 /., 143 

Zederbauer, 192 
Zoochlorella act in osph aerii, 

Zoospores, in Mycetozoa, 

40 ; in Proteomyxa, 4 
Zooteirea, 33 

zooxanthellae, in Radio- 

laria, 97 
Zopf, 2, 5, 6 n., 13, 39, 

60, 61, 67, 280, 281, 


Zuelzer, 71, 86, 87, 92 
Zygacantha, 146 ; Z. sep- 

tentrionalis, 146 
Zygoselmis, 171 

Printed by R. & R. CI.ARK, LIMITED, Edinburgh.